Method of making a semiconductor chip assembly with a copper/aluminum post/base heat spreader

ABSTRACT

A method of making a semiconductor chip assembly includes providing a post and a base that include a copper surface layer and an aluminum core, mounting an adhesive on the base including inserting the post into an opening in the adhesive, mounting a conductive layer on the adhesive including aligning the post with an aperture in the conductive layer, then flowing the adhesive into and upward in a gap located in the aperture between the post and the conductive layer, solidifying the adhesive, then providing a conductive trace that includes a pad, a terminal and a selected portion of the conductive layer, mounting a semiconductor device on a heat spreader that includes the post and the base, electrically connecting the semiconductor device to the conductive trace and thermally connecting the semiconductor device to the heat spreader.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No. 12/626,884filed Nov. 28, 2009, which is a continuation-in-part of U.S. applicationSer. No. 12/616,773 filed Nov. 11, 2009, which is incorporated byreference. U.S. application Ser. No. 12/626,884 filed Nov. 28, 2009 isalso a continuation-in-part of U.S. application Ser. No. 12/616,775filed Nov. 11, 2009, which is incorporated by reference. U.S.application Ser. No. 12/626,884 filed Nov. 28, 2009 also claims thebenefit of U.S. Provisional Application Ser. No. 61/250,492 filed Oct.9, 2009, which is incorporated by reference.

U.S. application Ser. No. 12/616,773 filed Nov. 11, 2009 and U.S.application Ser. No. 12/616,775 filed Nov. 11, 2009 are each acontinuation-in-part of U.S. application Ser. No. 12/557,540 filed Sep.11, 2009 and a continuation-in-part of U.S. application Ser. No.12/557,541 filed Sep. 11, 2009 now U.S. Pat. No. 7,948,076.

U.S. application Ser. No. 12/557,540 filed Sep. 11, 2009 and U.S.application Ser. No. 12/557,541 filed Sep. 11, 2009 are each acontinuation-in-part of U.S. application Ser. No. 12/406,510 filed Mar.18, 2009, which claims the benefit of U.S. Provisional Application Ser.No. 61/071,589 filed May 7, 2008, U.S. Provisional Application Ser. No.61/071,588 filed May 7, 2008, U.S. Provisional Application Ser. No.61/071,072 filed Apr. 11, 2008, and U.S. Provisional Application Ser.No. 61/064,748 filed Mar. 25, 2008, each of which is incorporated byreference. U.S. application Ser. No. 12/557,540 filed Sep. 11, 2009 andU.S. application Ser. No. 12/557,541 filed Sep. 11, 2009 also claim thebenefit of U.S. Provisional Application Ser. No. 61/150,980 filed Feb.9, 2009, which is incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to semiconductor chip assembly, and moreparticularly to a semiconductor chip assembly with a semiconductordevice, a conductive trace, an adhesive and a heat spreader and itsmethod of manufacture.

2. Description of the Related Art

Semiconductor devices such as packaged and unpackaged semiconductorchips have high voltage, high frequency and high performanceapplications that require substantial power to perform the specifiedfunctions. As the power increases, the semiconductor device generatesmore heat. Furthermore, the heat build-up is aggravated by higherpacking density and smaller profile sizes which reduce the surface areato dissipate the heat.

Semiconductor devices are susceptible to performance degradation as wellas short life span and immediate failure at high operating temperatures.The heat not only degrades the chip, but also imposes thermal stress onthe chip and surrounding elements due to thermal expansion mismatch. Asa result, the heat must be dissipated rapidly and efficiently from thechip to ensure effective and reliable operation. A high thermalconductivity path typically requires heat conduction and heat spreadingto a much larger surface area than the chip or a die pad it is mountedon.

Light emitting diodes (LEDs) have recently become popular alternativesto incandescent, fluorescent and halogen light sources. LEDs provideenergy efficient, cost effective, long term lighting for medical,military, signage, signal, aircraft, maritime, automotive, portable,commercial and residential applications. For instance, LEDs providelight sources for lamps, flashlights, headlights, flood lights, trafficlights and displays.

LEDs include high power chips that generate high light output andconsiderable heat. Unfortunately, LEDs exhibit color shifts and lowlight output as well as short lifetimes and immediate failure at highoperating temperatures. Furthermore, LED light output and reliabilityare constrained by heat dissipation limits. LEDs underscore the criticalneed for providing high power chips with adequate heat dissipation.

LED packages usually include an LED chip, a submount, electricalcontacts and a thermal contact. The submount is thermally connected toand mechanically supports the LED chip. The electrical contacts areelectrically connected to the anode and cathode of the LED chip. Thethermal contact is thermally connected to the LED chip by the submountbut requires adequate heat dissipation by the underlying carrier toprevent the LED chip from overheating.

Packages and thermal boards for high power chips have been developedextensively in the industry with a wide variety of designs andmanufacturing techniques in attempts to meet performance demands in anextremely cost-competitive environment.

Plastic ball grid array (PBGA) packages have a chip and a laminatedsubstrate enclosed in a plastic housing and are attached to a printedcircuit board (PCB) by solder balls. The laminated substrate includes adielectric layer that often includes fiberglass. The heat from the chipflows through the plastic and the dielectric layer to the solder ballsand then the PCB. However, since the plastic and the dielectric layertypically have low thermal conductivity, the PBGA provides poor heatdissipation.

Quad-Flat-No Lead (QFN) packages have the chip mounted on a copper diepad which is soldered to the PCB. The heat from the chip flows throughthe die pad to the PCB. However, since the lead frame type interposerhas limited routing capability, the QFN package cannot accommodate highinput/output (I/O) chips or passive elements.

Thermal boards provide electrical routing, thermal management andmechanical support for semiconductor devices. Thermal boards usuallyinclude a substrate for signal routing, a heat spreader or heat sink forheat removal, pads for electrical connection to the semiconductor deviceand terminals for electrical connection to the next level assembly. Thesubstrate can be a laminated structure with single layer or multi-layerrouting circuitry and one or more dielectric layers. The heat spreadercan be a metal base, a metal slug or an embedded metal layer.

Thermal boards interface with the next level assembly. For instance, thenext level assembly can be a light fixture with a printed circuit boardand a heat sink. In this instance, an LED package is mounted on thethermal board, the thermal board is mounted on the heat sink, thethermal board/heat sink subassembly and the printed circuit board aremounted in the light fixture and the thermal board is electricallyconnected to the printed circuit board by wires. The substrate routeselectrical signals to the LED package from the printed circuit board andthe heat spreader spreads and transfers heat from the LED package to theheat sink. The thermal board thus provides a critical thermal path forthe LED chip.

U.S. Pat. No. 6,507,102 to Juskey et al. discloses an assembly in whicha composite substrate with fiberglass and cured thermosetting resinincludes a central opening, a heat slug with a square or rectangularshape resembling the central opening is attached to the substrate atsidewalls of the central opening, top and bottom conductive layers areattached to the top and bottom of the substrate and electricallyconnected to one another by plated through-holes through the substrate,a chip is mounted on the heat slug and wire bonded to the top conductivelayer, an encapsulant is molded on the chip and solder balls are placedon the bottom conductive layer.

During manufacture, the substrate is initially a prepreg with B-stageresin placed on the bottom conductive layer, the heat slug is insertedinto the central opening and on the bottom conductive layer and spacedfrom the substrate by a gap, the top conductive layer is mounted on thesubstrate, the conductive layers are heated and pressed towards oneanother so that the resin melts, flows into the gap and solidifies, theconductive layers are patterned to form circuit traces on the substrateand expose the excess resin flash on the heat slug, and the excess resinflash is removed to expose the heat slug. The chip is then mounted onthe heat slug, wire bonded and encapsulated.

The heat flows from the chip through the heat slug to the PCB. However,manually dropping the heat slug into the central opening isprohibitively cumbersome and expensive for high volume manufacture.Furthermore, since the heat slug is difficult to accurately position inthe central opening due to tight lateral placement tolerance, voids andinconsistent bond lines arise between the substrate and the heat slug.The substrate is therefore partially attached to the heat slug, fragiledue to inadequate support by the heat slug and prone to delamination. Inaddition, the wet chemical etch that removes portions of the conductivelayers to expose the excess resin flash also removes portions of theheat slug exposed by the excess resin flash. The heat slug is thereforenon-planar and difficult to bond to. As a result, the assembly suffersfrom high yield loss, poor reliability and excessive cost.

U.S. Pat. No. 6,528,882 to Ding et al. discloses a thermal enhanced ballgrid array package in which the substrate includes a metal core layer.The chip is mounted on a die pad region at the top surface of the metalcore layer, an insulating layer is formed on the bottom surface of themetal core layer, blind vias extend through the insulating layer to themetal core layer, thermal balls fill the blind vias and solder balls areplaced on the substrate and aligned with the thermal balls. The heatfrom the chip flows through the metal core layer to the thermal balls tothe PCB. However, the insulating layer sandwiched between the metal corelayer and the PCB limits the heat flow to the PCB.

U.S. Pat. No. 6,670,219 to Lee et al. discloses a cavity down ball gridarray (CDBGA) package in which a ground plate with a central opening ismounted on a heat spreader to form a thermal dissipating substrate. Asubstrate with a central opening is mounted on the ground plate using anadhesive with a central opening. A chip is mounted on the heat spreaderin a cavity defined by the central opening in the ground plate andsolder balls are placed on the substrate. However, since the solderballs extend above the substrate, the heat spreader does not contact thePCB. As a result, the heat spreader releases the heat by thermalconvection rather than thermal conduction which severely limits the heatdissipation.

U.S. Pat. No. 7,038,311 to Woodall et al. discloses a thermal enhancedBGA package in which a heat sink with an inverted T-like shape includesa pedestal and an expanded base, a substrate with a window opening ismounted on the expanded base, an adhesive attaches the pedestal and theexpanded base to the substrate, a chip is mounted on the pedestal andwire bonded to the substrate, an encapsulant is molded on the chip andsolder balls are placed on the substrate. The pedestal extends throughthe window opening, the substrate is supported by the expanded base andthe solder balls are located between the expanded base and the perimeterof the substrate. The heat from the chip flows through the pedestal tothe expanded base to the PCB. However, since the expanded base mustleave room for the solder balls, the expanded base protrudes below thesubstrate only between the central window and the innermost solder ball.Consequently, the substrate is unbalanced and wobbles and warps duringmanufacture. This creates enormous difficulties with chip mounting, wirebonding and encapsulant molding. Furthermore, the expanded base may bebent by the encapsulant molding and may impede soldering the package tothe next level assembly as the solder balls collapse. As a result, thepackage suffers from high yield loss, poor reliability and excessivecost.

U.S. Patent Application Publication No. 2007/0267642 to Erchak et al.discloses a light emitting device assembly in which a base with aninverted T-like shape includes a substrate, a protrusion and aninsulative layer with an aperture, electrical contacts are mounted onthe insulative layer, a package with an aperture and a transparent lidis mounted on the electrical contacts and an LED chip is mounted on theprotrusion and wire bonded to the substrate. The protrusion is adjacentto the substrate and extends through the apertures in the insulativelayer and the package into the package, the insulative layer is mountedon the substrate, the electrical contacts are mounted on the insulativelayer and the package is mounted on the electrical contacts and spacedfrom the insulative layer. The heat from the chip flows through theprotrusion to the substrate to a heat sink. However, the electricalcontacts are difficult to mount on the insulating layer, difficult toelectrically connect to the next level assembly and fail to providemulti-layer routing.

Conventional packages and thermal boards thus have major deficiencies.For instance, dielectrics with low thermal conductivity such as epoxylimit heat dissipation, whereas dielectrics with higher thermalconductivity such as epoxy filled with ceramic or silicon carbide havelow adhesion and are prohibitively expensive for high volumemanufacture. The dielectric may delaminate during manufacture orprematurely during operation due to the heat. The substrate may havesingle layer circuitry with limited routing capability or multi-layercircuitry with thick dielectric layers which reduce heat dissipation.The heat spreader may be inefficient, cumbersome or difficult tothermally connect to the next level assembly. The manufacturing processmay be unsuitable for low cost, high volume manufacture.

Conventional heat spreaders are typically copper since copper has highthermal conductivity, good bondability and low cost. Aluminum issignificantly lighter and less expensive that copper. However, aluminumis difficult to plate, solder and wire bond to since it oxidizesrapidly. Furthermore, aluminum has a higher coefficient of thermalexpansion and lower structural integrity than copper. As a result,aluminum heat spreaders have major drawbacks.

In view of the various development stages and limitations in currentlyavailable packages and thermal boards for high power semiconductordevices, there is a need for a semiconductor chip assembly that is costeffective, reliable, manufacturable, versatile, provides flexible signalrouting and has excellent heat spreading and dissipation.

SUMMARY OF THE INVENTION

The present invention provides a semiconductor chip assembly thatincludes a semiconductor device, a heat spreader, a conductive trace andan adhesive. The semiconductor device is electrically connected to theconductive trace and thermally connected to the heat spreader. The heatspreader includes a post and a base that include a copper surface layerand an aluminum core. The post extends upwardly from the base into anopening in the adhesive, and the base extends laterally from the post.The adhesive extends between the post and the conductive trace andbetween the base and the conductive trace. The conductive trace providessignal routing between a pad and a terminal.

In accordance with an aspect of the present invention, a semiconductorchip assembly includes a semiconductor device, an adhesive, a heatspreader and a conductive trace. The adhesive includes an opening. Theheat spreader includes a post and a base, wherein the post is adjacentto the base and extends above the base in an upward direction, and thebase extends below the post in a downward direction opposite the upwarddirection and extends laterally from the post in lateral directionsorthogonal to the upward and downward directions. The post and the baseinclude a copper surface layer and an aluminum core, wherein the coppersurface layer conformally coats and extends above the aluminum core andthe aluminum core of the post extends above the copper surface layer ofthe base. The conductive trace includes a pad and a terminal.

The semiconductor device is above and overlaps the post, is electricallyconnected to the pad and thereby electrically connected to the terminal,and is thermally connected to the post and thereby thermally connectedto the base. The adhesive is mounted on and extends above the base,extends into a gap between the post and the pad, extends laterally fromthe post to or beyond the terminal and is sandwiched between the baseand the pad. The pad is mounted on the adhesive and extends above thebase. The post extends into the opening, and the base extends below thesemiconductor device, the adhesive and the pad.

The conductive trace can include the pad, the terminal and a routingline, an electrically conductive path between the pad and the terminalcan include the routing line and the pad, the terminal and the routingline can contact and overlap the adhesive.

In accordance with another aspect of the present invention, asemiconductor chip assembly includes a semiconductor device, anadhesive, a heat spreader, a substrate and a terminal. The adhesiveincludes an opening. The heat spreader includes a post and a base,wherein the post is adjacent to the base and extends above the base inan upward direction, and the base extends below the post in a downwarddirection opposite the upward direction and extends laterally from thepost in lateral directions orthogonal to the upward and downwarddirections. The post and the base include a copper surface layer and analuminum core, wherein the copper surface layer conformally coats andextends above the aluminum core and the aluminum core of the postextends above the copper surface layer of the base. The substrateincludes a pad and a dielectric layer, and an aperture extends throughthe substrate.

The semiconductor device is above and overlaps the post, is electricallyconnected to the pad and thereby electrically connected to the terminal,and is thermally connected to the post and thereby thermally connectedto the base. The adhesive is mounted on and extends above the base,extends into a gap in the aperture between the post and the substrate,extends across the dielectric layer in the gap, extends laterally fromthe post to or beyond the terminal and is sandwiched between the postand the dielectric layer and between the base and the substrate. Thesubstrate is mounted on the adhesive and extends above the base. Thepost extends into the opening and the aperture, and the base extendsbelow the semiconductor device, the adhesive and the substrate.

The heat spreader can include a cap that is above and adjacent to andcovers in the upward direction and extends laterally in the lateraldirections from a top of the post. For instance, the cap can have arectangular or square shape and the top of the post can have a circularshape. In this instance, the cap can be sized and shaped to accommodatea thermal contact surface of the semiconductor device whereas the top ofthe post is not sized and shaped to accommodate the thermal contactsurface of the semiconductor device. The cap can also contact and covera portion of the adhesive that is coplanar with and adjacent to thepost. The cap can also be coplanar with the pad and/or the terminalabove the dielectric layer. The cap can also be copper and the coppersurface layer can provide the top of the post. In addition, the post canthermally connect the base and the cap.

The heat spreader can consist of the post and the base or the post, thebase and the cap. The heat spreader can also include a nickel bufferlayer that contacts and is sandwiched between and separates the aluminumcore and the copper surface layer. The heat spreader can also consist ofcopper/nickel/aluminum although an amorphous spotty random monolayer ofzinc or palladium may reside between the aluminum core and the nickelbuffer layer. The heat spreader can also be primarily aluminum. In anycase, the heat spreader provides heat dissipation and spreading from thesemiconductor device to the next level assembly.

The copper surface layer can conformally coat and extend above thealuminum core and covers the aluminum core in the upward direction, thealuminum core can extend below the copper surface layer and cover thecopper surface layer in the downward direction, the aluminum core of thepost can extend above the copper surface layer of the base, and thecopper surface layer of the post can cover and surround the aluminumcore of the post in the lateral directions. Furthermore, the postaluminum core height can be greater than the base aluminum corethickness and greater than five times the copper surface layerthickness, and the base aluminum core thickness can be greater than thecopper surface layer thickness.

The semiconductor device can be mounted on the heat spreader. Forinstance, the semiconductor device can be mounted on the heat spreaderand the substrate, overlap the post and the pad, be electricallyconnected to the pad using a first solder joint and be thermallyconnected to the heat spreader using a second solder joint.Alternatively, the semiconductor device can be mounted on the heatspreader but not the substrate, overlap the post but not the substrate,be electrically connected to the pad using a wire bond and be thermallyconnected to the heat spreader using a die attach.

The semiconductor device can be a packaged or unpackaged semiconductorchip. For instance, the semiconductor device can be an LED package thatincludes an LED chip, is mounted on the heat spreader and the substrate,overlaps the post and the pad, is electrically connected to the padusing a first solder joint and is thermally connected to the heatspreader using a second solder joint. Alternatively, the semiconductordevice can be a semiconductor chip that is mounted on the heat spreaderbut not the substrate, overlaps the post but not the substrate, iselectrically connected to the pad using a wire bond and is thermallyconnected to the heat spreader using a die attach.

The adhesive can contact the post and the dielectric layer in the gapand contact the base and the dielectric layer outside the gap. Theadhesive can also contact the copper surface layer and be spaced fromthe aluminum core. The adhesive can also cover the substrate in thedownward direction, cover and surround the post in the lateraldirections and cover the base outside the post in the upward direction.The adhesive can also conformally coat the sidewalls of the post and atop surface of the base outside the post. The adhesive can also becoplanar with a top of the post. The adhesive can also fill the spacebetween the post and the dielectric layer, fill the space between thebase and the substrate and be contained in the space between the heatspreader and the substrate.

The adhesive can extend laterally from the post to or beyond theterminal. For instance, the adhesive and the terminal can extend toperipheral edges of the assembly. In this instance, the adhesive extendslaterally from the post to the terminal. Alternatively, the adhesive canextend to peripheral edges of the assembly and the terminal can bespaced from the peripheral edges of the assembly. In this instance, theadhesive extends laterally from the post beyond the terminal.

The adhesive can overlap or be overlapped by the terminal. For instance,the terminal can extend above and overlap the dielectric layer and theadhesive and be coplanar with the pad and the cap. In this instance, theadhesive is overlapped by the terminal and the assembly provideshorizontal signal routing between the pad and the terminal.Alternatively, the terminal can extend below and be overlapped by thedielectric layer and the adhesive and be coplanar with the base. In thisinstance, the adhesive overlaps the terminal and the assembly providesvertical signal routing between the pad and the terminal.

The post can be integral with the base. For instance, the post and thebase can include single-piece aluminum, single-piece nickel andsingle-piece copper stack at their interface. The post can also extendthrough the aperture. The post can also be coplanar with the adhesiveabove the dielectric layer. The post can also have a cut-off conicalshape in which its diameter decreases as it extends upwardly from thebase to its flat top.

The base can cover the semiconductor device, the post, the cap, theadhesive and the substrate in the downward direction, support thesubstrate and extend to peripheral edges of the assembly.

The substrate can be spaced from the post and the base. The substratecan also be a laminated structure. The substrate can also include asingle conductive layer or multiple conductive layers. For instance, thesubstrate can include a single conductive layer that contacts andextends above the dielectric layer. In this instance, the conductivelayer includes the pad and the terminal. Thus, the substrate includesthe terminal, the adhesive is overlapped by the terminal and the signalrouting between the pad and the terminal occurs above but not throughthe dielectric layer. Alternatively, the substrate can include a firstconductive layer that contacts and extends above the dielectric layer, asecond conductive layer that contacts and extends below the dielectriclayer, and a via that extends through the dielectric layer andelectrically connects the conductive layers. In this instance, the firstconductive layer includes the pad. Furthermore, (1) the first conductivelayer includes the terminal and the substrate includes another via thatextends through the dielectric layer and electrically connects theconductive layers, in which case the substrate includes the terminal,the adhesive is overlapped by the terminal and the signal routingbetween the pad and the terminal occurs through the dielectric layer butnot the adhesive, or alternatively, (2) the terminal is below theadhesive and the substrate and the assembly includes another via thatextends through the adhesive and electrically connects the terminal andthe second conductive layer, in which case the substrate excludes theterminal, the adhesive overlaps the terminal and the signal routingbetween the pad and the terminal occurs through the dielectric layer andthe adhesive. In any case, the substrate includes the pad and providessome or all of the signal routing between the pad and the terminal.

The pad can be an electrical contact for the semiconductor device, theterminal can be an electrical contact for the next level assembly, andthe pad and the terminal can provide signal routing between thesemiconductor device and the next level assembly.

The assembly can be a first-level or second-level single-chip ormulti-chip device. For instance, the assembly can be a first-levelpackage that contains a single chip or multiple chips. Alternatively,the assembly can be a second-level module that contains a single LEDpackage or multiple LED packages, and each LED package can contain asingle LED chip or multiple LED chips.

The present invention provides a method of making a semiconductor chipassembly that includes providing a post and a base that include a coppersurface layer and an aluminum core, mounting an adhesive on the baseincluding inserting the post into an opening in the adhesive, mounting aconductive layer on the adhesive including aligning the post with anaperture in the conductive layer, then flowing the adhesive into andupward in a gap located in the aperture between the post and theconductive trace, solidifying the adhesive, then providing a conductivetrace that includes a pad, a terminal and a selected portion of theconductive layer, mounting a semiconductor device on a heat spreaderthat includes the post and the base, electrically connecting thesemiconductor device to the conductive trace and thermally connectingthe semiconductor device to the heat spreader.

In accordance with an aspect of the present invention, a method ofmaking a semiconductor chip assembly includes (1) providing a post, abase, an adhesive and a conductive layer, wherein (a) the post isadjacent to the base, extends above the base in an upward direction,extends into an opening in the adhesive and is aligned with an aperturein the conductive layer, (b) the base extends below the post in adownward direction opposite the upward direction and extends laterallyfrom the post in lateral directions orthogonal to the upward anddownward directions, (c) the post and the base include a copper surfacelayer and an aluminum core, the copper surface layer conformally coatsand extends above the aluminum core, and the aluminum core of the postextends above the copper surface layer of the base, (d) the adhesive ismounted on and extends above the base, is sandwiched between the baseand the conductive layer and is non-solidified, and (e) the conductivelayer is mounted on and extends above the adhesive, then (2) flowing theadhesive into and upward in a gap located in the aperture between thepost and the conductive layer, (3) solidifying the adhesive, then (4)providing a conductive trace that includes a pad, a terminal and aselected portion of the conductive layer, (5) mounting a semiconductordevice on a heat spreader that includes the post and the base, whereinthe semiconductor device overlaps the post, (6) electrically connectingthe semiconductor device to the pad, thereby electrically connecting thesemiconductor device to the terminal, and (7) thermally connecting thesemiconductor device to the post, thereby thermally connecting thesemiconductor device to the base.

In accordance with another aspect of the present invention, a method ofmaking a semiconductor chip assembly includes (1) providing a post and abase, wherein the post is adjacent to and integral with the base andextends above the base in an upward direction, the base extends belowthe post in a downward direction opposite the upward direction andextends laterally from the post in lateral directions orthogonal to theupward and downward directions, the post and the base include a coppersurface layer and an aluminum core, the copper surface layer conformallycoats and extends above the aluminum core, and the aluminum core of thepost extends above the copper surface layer of the base, (2) providingan adhesive, wherein an opening extends through the adhesive, (3)providing a conductive layer, wherein an aperture extends through theconductive layer, (4) mounting the adhesive on the base, includinginserting the post into the opening, wherein the adhesive extends abovethe base and the post extends through the opening, (5) mounting theconductive layer on the adhesive, including aligning the post with theaperture, wherein the conductive layer extends above the adhesive andthe adhesive is sandwiched between the base and the conductive layer andis non-solidified, then (6) applying heat to melt the adhesive, (7)moving the base and the conductive layer towards one another, therebymoving the post upward in the aperture and applying pressure to themolten adhesive between the base and the conductive layer, wherein thepressure forces the molten adhesive to flow into and upward in a gaplocated in the aperture between the post and the conductive layer, (8)applying heat to solidify the molten adhesive, thereby mechanicallyattaching the post and the base to the conductive layer, then (9)providing a conductive trace that includes a pad and a terminal, whereinthe conductive trace includes selected portions of the conductive layerand an electrically conductive path is between the pad and the terminal,(10) mounting a semiconductor device on a heat spreader that includesthe post and the base, wherein the semiconductor device overlaps thepost, (11) electrically connecting the semiconductor device to the pad,thereby electrically connecting the semiconductor device to theterminal, and (12) thermally connecting the semiconductor device to thepost, thereby thermally connecting the semiconductor device to the base.

Mounting the conductive layer can include mounting the conductive layeralone on the adhesive, or alternatively, attaching the conductive layerto a carrier, then mounting the conductive layer and the carrier on theadhesive such that the carrier overlaps the conductive layer and theconductive layer contacts the adhesive and is sandwiched between theadhesive and the carrier, and then, after solidifying the adhesive,removing the carrier and then providing the conductive trace.

In accordance with another aspect of the present invention, a method ofmaking a semiconductor chip assembly includes (1) providing a post, abase, an adhesive and a substrate, wherein (a) the substrate includes aconductive layer and a dielectric layer, (b) the post is adjacent to thebase, extends above the base in an upward direction, extends through anopening in the adhesive and extends into an aperture in the substrate,(c) the base extends below the post in a downward direction opposite theupward direction and extends laterally from the post in lateraldirections orthogonal to the upward and downward directions, (d) thepost and the base include an aluminum core and a copper surface layer,the aluminum core of the post extends above the copper surface layer ofthe base and the copper surface layer conformally coats and extendsabove the aluminum core, (e) the adhesive is mounted on and extendsabove the base, is sandwiched between the base and the substrate and isnon-solidified, (f) the substrate is mounted on and extends above theadhesive and the conductive layer extends above the dielectric layer,and (g) a gap is located in the aperture between the post and thesubstrate, then (2) flowing the adhesive into and upward in the gap, (3)solidifying the adhesive, then (4) mounting a semiconductor device on aheat spreader that includes the post and the base, wherein thesemiconductor device overlaps the post, a conductive trace includes apad, a terminal and a selected portion of the conductive layer and thepad is electrically connected to the terminal, (5) electricallyconnecting the semiconductor device to the pad, thereby electricallyconnecting the semiconductor device to the terminal, and (6) thermallyconnecting the semiconductor device to the post, thereby thermallyconnecting the semiconductor device to the base.

In accordance with another aspect of the present invention, a method ofmaking a semiconductor chip assembly includes (1) providing a post and abase, wherein the post is adjacent to and integral with the base andextends above the base in an upward direction, the base extends belowthe post in a downward direction opposite the upward direction andextends laterally from the post in lateral directions orthogonal to theupward and downward directions, the post and the base include analuminum core and a copper surface layer, the aluminum core of the postextends above the copper surface layer of the base and the coppersurface layer conformally coats and extends above the aluminum core, (2)providing an adhesive, wherein an opening extends through the adhesive,(3) providing a substrate that includes a conductive layer and adielectric layer, wherein an aperture extends through the substrate, (4)mounting the adhesive on the base, including inserting the post throughthe opening, wherein the adhesive extends above the base and the postextends through the opening, (5) mounting the substrate on the adhesive,including inserting the post into the aperture, wherein the substrateextends above the adhesive, the conductive layer extends above thedielectric layer, the post extends through the opening into theaperture, the adhesive is sandwiched between the base and the substrateand is non-solidified, and a gap is located in the aperture between thepost and the substrate, then (6) applying heat to melt the adhesive, (7)moving the base and the substrate towards one another, thereby movingthe post upward in the aperture and applying pressure to the moltenadhesive between the base and the substrate, wherein the pressure forcesthe molten adhesive to flow into and upward in the gap and the post andthe molten adhesive extend above the dielectric layer, (8) applying heatto solidify the molten adhesive, thereby mechanically attaching the postand the base to the substrate, then (9) mounting a semiconductor deviceon a heat spreader that includes the post and the base, wherein thesemiconductor device overlaps the post, a conductive trace includes apad, a terminal and a selected portion of the conductive layer and thepad is electrically connected to the terminal, (10) electricallyconnecting the semiconductor device to the pad, thereby electricallyconnecting the semiconductor device to the terminal, and (11) thermallyconnecting the semiconductor device to the post, thereby thermallyconnecting the semiconductor device to the base.

Providing the post and the base can include providing an aluminum plate,forming an etch mask on the aluminum plate that selectively exposes thealuminum plate, etching the aluminum plate in a pattern defined by theetch mask, thereby forming a recess in the aluminum plate that extendsinto but not through the aluminum plate, and then removing the etchmask, wherein the aluminum core of the post is an unetched portion ofthe aluminum plate that is laterally surrounded by the recess, and thealuminum core of the base is an unetched portion of the aluminum platebelow the recess.

Providing the post and the base can also include electrolessly plating anickel buffer layer on the aluminum core, electrolessly plating a firstcopper layer on the nickel buffer layer, and electroplating a secondcopper layer on the first copper layer, wherein the copper surface layerincludes the first and second copper layers.

Providing the adhesive can include providing a prepreg with uncuredepoxy, flowing the adhesive can include melting the uncured epoxy andcompressing the uncured epoxy between the base and the substrate, andsolidifying the adhesive can include curing the molten uncured epoxy.

Providing the heat spreader can include grinding the post, the adhesiveand the conductive layer such that the post, the adhesive and theconductive layer are laterally aligned with one another at a top lateralsurface that includes the copper surface layer, excludes the nickelbuffer layer and the aluminum core and faces in the upward direction.The grinding can include grinding the adhesive without grinding the postand then grinding the post, the adhesive and the conductive layer. Thegrinding can also remove about one-half the thickness of the coppersurface layer at the top of the post, thereby leaving the copper surfacelayer at the top of the post intact. In any case, the grinding haltsbefore it reaches the nickel buffer layer or the aluminum core.

Providing the heat spreader can also include providing a cap on the postthat is above and adjacent to and covers in the upward direction andextends laterally in the lateral directions from a top of the post aftersolidifying the adhesive and before mounting the semiconductor device.

Providing the pad can include removing selected portions of theconductive layer after solidifying the adhesive.

Providing the pad can also include removing selected portions of theconductive layer after the grinding such that the pad includes selectedportions of the conductive layer. The removing can include applying awet chemical etch to the conductive layer using an etch mask thatdefines the pad.

Providing the pad can also include depositing a second conductive layeron the post, the adhesive and the conductive layer after the grindingand then removing selected portions of the conductive layers such thatthe pad includes selected portions of the conductive layers. Depositingthe second conductive layer can include electrolessly plating a firstplated layer on the post, the adhesive and the conductive layer and thenelectroplating a second plated layer on the first plated layer. Theremoving can include applying the wet chemical etch to the conductivelayers using the etch mask to define the pad.

Providing the terminal can include removing selected portions of theconductive layer after solidifying the adhesive. Providing the terminalcan also include the grinding and then removing selected portions of theconductive layer using the etch mask to define the terminal such thatthe terminal includes selected portions of the conductive layer.Providing the terminal can also include the grinding and then removingselected portions the conductive layers using the etch mask to definethe terminal such that the terminal includes selected portions of theconductive layers. Thus, the pad and the terminal can be formedsimultaneously using the same grinding, wet chemical etch and etch mask.

Providing the cap can include removing selected portions of the secondconductive layer. Providing the cap can also include the grinding andthen removing selected portions of the second conductive layer using theetch mask to define the cap such that the cap includes selected portionsof the second conductive layer. Thus, the pad and the cap can be formedsimultaneously using the same grinding, wet chemical etch and etch maskLikewise, the pad, the terminal and the cap can be formed simultaneouslyusing the same grinding, wet chemical etch and etch mask.

Flowing the adhesive can include filling the gap with the adhesive.Flowing the adhesive can also include squeezing the adhesive through thegap, above the post and the substrate and on top surface portions of thepost and the substrate adjacent to the gap.

Solidifying the adhesive can include mechanically bonding the post andthe base to the substrate.

Mounting the semiconductor device can include mounting the semiconductordevice on the post or the cap. Mounting the semiconductor device canalso include positioning the semiconductor device above and overlappingthe post, the opening and the aperture.

Mounting the semiconductor device can include providing a first solderjoint between an LED package that includes an LED chip and the pad and asecond solder joint between the LED package and the heat spreader,electrically connecting the semiconductor device can include providingthe first solder joint between the LED package and the pad, andthermally connecting the semiconductor device can include providing thesecond solder joint between the LED package and the heat spreader.

Mounting the semiconductor device can include providing a die attachbetween a semiconductor chip and the heat spreader, electricallyconnecting the semiconductor device can include providing a wire bondbetween the chip and the pad, and thermally connecting the semiconductordevice can include providing the die attach between the chip and theheat spreader.

The adhesive can contact the post, the base, the cap and the dielectriclayer, contact the copper surface layer and be spaced from the nickelbuffer layer and the aluminum core, cover the substrate in the downwarddirection, cover and surround the post in the lateral directions andextend to peripheral edges of the assembly after the assembly ismanufactured and detached from other assemblies in a batch.

The base can cover the semiconductor device, the post, the cap, theadhesive and the substrate in the downward direction, support thesubstrate and extend to peripheral edges of the assembly after theassembly is manufactured and detached from other assemblies in a batch.

The present invention has numerous advantages. The heat spreader canprovide excellent heat spreading and heat dissipation without heat flowthrough the adhesive. As a result, the adhesive can be a low costdielectric with low thermal conductivity and not prone to delamination.The post and the base can be integral with one another, therebyenhancing reliability. The post and the base can also be primarilyaluminum with a copper surface layer, thereby maintaining bondabilityand reducing cost. The cap can be customized for the semiconductordevice, thereby enhancing the thermal connection. The adhesive can besandwiched between the post and the substrate and between the base andthe substrate, thereby providing a robust mechanical bond between theheat spreader and the substrate. The substrate can provide single-layersignal routing with simple circuitry patterns or flexible multi-layersignal routing with complex circuitry patterns. The conductive trace canprovide horizontal signal routing between the pad and the terminal abovethe dielectric layer or vertical signal routing between the pad abovethe dielectric layer and the terminal below the adhesive. The base canprovide mechanical support for the substrate, thereby preventingwarping. The assembly can be manufactured using low temperatureprocesses which reduces stress and improves reliability. The assemblycan also be manufactured using well-controlled processes which can beeasily implemented by circuit board, lead frame and tape manufacturers.

These and other features and advantages of the present invention will befurther described and more readily apparent from a review of thedetailed description of the preferred embodiments which follows.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed description of the preferred embodiments of thepresent invention can best be understood when read in conjunction withthe following drawings, in which:

FIGS. 1A-1F are cross-sectional views showing a method of making a postand a base in accordance with an embodiment of the present invention;

FIGS. 1G and 1H are top and bottom views, respectively, corresponding toFIG. 1F;

FIGS. 2A and 2B are cross-sectional views showing a method of making anadhesive in accordance with an embodiment of the present invention;

FIGS. 2C and 2D are top and bottom views, respectively, corresponding toFIG. 2B;

FIGS. 3A and 3B are cross-sectional views showing a method of making asubstrate in accordance with an embodiment of the present invention;

FIGS. 3C and 3D are top and bottom views, respectively, corresponding toFIG. 3B;

FIGS. 4A-4L are cross-sectional views showing a method of making athermal board with horizontal signal routing in accordance with anembodiment of the present invention;

FIGS. 4M and 4N are top and bottom views, respectively, corresponding toFIG. 4L;

FIGS. 5A, 5B and 5C are cross-sectional, top and bottom views,respectively, of a thermal board with vertical signal routing inaccordance with an embodiment of the present invention;

FIGS. 6A, 6B and 6C are cross-sectional, top and bottom views,respectively, of a thermal board with a conductive trace on an adhesivein accordance with an embodiment of the present invention;

FIGS. 7A, 7B and 7C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly that includes a thermalboard and an LED package with backside contacts accordance with anembodiment of the present invention;

FIGS. 8A, 8B and 8C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly that includes a thermalboard and an LED package with lateral leads in accordance with anembodiment of the present invention;

FIGS. 9A, 9B and 9C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly that includes a thermalboard with horizontal signal routing and a semiconductor chip inaccordance with an embodiment of the present invention;

FIGS. 10A, 10B and 10C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly that includes a thermalboard with vertical signal routing and a semiconductor chip inaccordance with an embodiment of the present invention; and

FIGS. 11A, 11B and 11C are cross-sectional, top and bottom views,respectively, of a light source subassembly that includes asemiconductor chip assembly and a heat sink in accordance with anembodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1A-1F are cross-sectional views showing a method of making a postand a base in accordance with an embodiment of the present invention,and FIGS. 1G and 1H are top and bottom views, respectively,corresponding to FIG. 1F.

FIG. 1A is a cross-sectional view of aluminum plate 10 which includesopposing major surfaces 12 and 14 and has a thickness of 500 microns.

FIG. 1B is a cross-sectional view of etch mask 16 and cover mask 18formed on aluminum plate 10. Etch mask 16 and cover mask 18 areillustrated as photoresist layers which are deposited on aluminum plate10 using dry film lamination in which hot rolls simultaneously pressphotoresist layers 16 and 18 onto surfaces 12 and 14, respectively. Wetspin coating and curtain coating are also suitable depositiontechniques. A reticle (not shown) is positioned proximate to photoresistlayer 16. Thereafter, photoresist layer 16 is patterned by selectivelyapplying light through the reticle so that the photoresist portionsexposed to the light are rendered insoluble, applying a developersolution to remove the photoresist portions that are unexposed to thelight and remain soluble and then hard baking, as is conventional. As aresult, photoresist layer 16 has a pattern that selectively exposessurface 12, and photoresist layer 18 remains unpatterned and coverssurface 14.

FIG. 1C is a cross-sectional view of recess 20 formed into but notthrough aluminum plate 10 by etching aluminum plate 10 in the patterndefined by etch mask 16. The etching is illustrated as a front-side wetchemical etch. For instance, the structure can be inverted so that etchmask 16 faces downward and cover mask 18 faces upward as a bottom spraynozzle (not shown) that faces etch mask 16 upwardly sprays the wetchemical etch on aluminum plate 10 and etch mask 16 while a top spraynozzle (not shown) that faces cover mask 18 is deactivated so thatgravity assists with removing the etched byproducts. Alternatively, thestructure can be dipped in the wet chemical etch since cover mask 18provides back-side protection. The wet chemical etch is highly selectiveof aluminum and etches 300 microns into aluminum plate 10. As a result,recess 20 extends from surface 12 into but not through aluminum plate10, is spaced from surface 14 by 200 microns and has a depth of 300microns. The wet chemical etch also laterally undercuts aluminum plate10 beneath etch mask 16. A suitable wet chemical etch can be provided byan acidic solution containing ferric chloride or a mixture of nitricacid and phosphoric acid. Likewise, the wet chemical etch can bealkaline. The optimal etch time for forming recess 20 withoutexcessively exposing aluminum plate 10 to the wet chemical etch can beestablished through trial and error.

FIG. 1D is a cross-sectional view of aluminum plate 10 after etch mask16 and cover mask 18 are removed. The photoresist layers are strippedusing a solvent, such as a strong alkaline solution containing potassiumhydroxide with a pH of 14, that is highly selective of photoresist withrespect to aluminum. Aluminum plate 10 as etched provides aluminum core22.

FIG. 1E is a cross-sectional view of the structure with nickel bufferlayer 24 deposited on aluminum core 22. Nickel buffer layer 24 contactsand conformally coats aluminum core 22 and covers aluminum core 22 inthe upwards direction. For instance, the aluminum core 22 is dipped in azinc activator solution to render aluminum core 22 catalytic toelectroless nickel, and then nickel buffer layer 24 is electrolesslyplated on zincated aluminum core 22. Nickel buffer layer 24 has athickness of 3 microns.

FIGS. 1F, 1G and 1H are cross-sectional, top and bottom views,respectively, of copper surface layer 26 formed on the structure.

Copper surface layer 26 contacts nickel buffer layer 24, is separatedfrom aluminum core 22 by nickel buffer layer 24 and covers aluminum core22 and nickel buffer layer 24 in the upwards direction. Copper surfacelayer 26 conformally coats and extends above aluminum core 22 and nickelbuffer layer 24, nickel buffer layer 24 contacts and is sandwichedbetween aluminum core 22 and copper surface layer 26, and aluminum core22 extends below nickel buffer layer 24 and copper surface layer 26 andcovers nickel buffer layer 24 and copper surface layer 26 in thedownward direction.

For instance, a first copper layer is electrolessly plated on nickelbuffer layer 24, and then a second copper layer is electroplated on thefirst copper layer. The first copper layer has a thickness of 2 microns,the second copper layer has a thickness of 25 microns, and coppersurface layer 26 has a thickness of 27 microns.

Aluminum core 22, nickel buffer layer 24 and copper surface layer 26provide post 30 and base 32. Likewise, post 30 and base 32 includealuminum core 22, nickel buffer layer 24 and copper surface layer 26.

Post 30 is an unetched portion of aluminum plate 10 defined by etch mask16 and surrounded by recess 20 that is subsequently coated with nickelbuffer layer 24 and copper surface layer 26. Post 30 is adjacent to andintegral with and protrudes above base 32. Post 30 has a height of 300microns (recess 20 depth), a diameter at its top surface (circularportion of surface 12) of 1000 microns and a diameter at its bottom(circular portion adjacent to base 32) of 1100 microns. Thus, post 30has a cut-off conical shape (resembling a frustum) with taperedsidewalls in which its diameter decreases as it extends upwardly frombase 32 to its flat circular top surface. The tapered sidewalls arisefrom the lateral undercutting by the wet chemical etch beneath etch mask16. The top surface is concentrically disposed within a periphery of thebottom (shown in phantom in FIG. 1G).

Base 32 is an unetched portion of aluminum plate 10 below recess 20 thatis subsequently coated with nickel buffer layer 24 and copper surfacelayer 26. Base 32 extends laterally from post 30 in a lateral plane(with lateral directions such as left and right) and has a thickness of230 microns (500−300+3+27).

The aluminum core of post 30 has a height of 300 microns above thealuminum core of base 30 and extends 270 microns (300−30) above thecopper surface layer of the base 32, the aluminum core of base 32 has athickness of 200 microns, and copper surface layer 26 has a thickness of27 microns. Therefore, the aluminum core of post 30 has a height abovethe aluminum core of base 32 (300 microns) that is greater thanthickness the aluminum core of base 32 (200 microns) and is greater thanfive times the thickness of copper surface layer 26 (27 microns).

Post 30 and base 32 can be treated to improve bondability to epoxy andsolder. For instance, post 30 and base 32 can be chemically oxidized ormicroetched to provide rougher surfaces.

Post 30 and base 32 are illustrated as semi-additively formed bydepositing nickel buffer layer 24 and copper surface layer 26 onsubtractively formed aluminum core 22. Post 30 and base 32 can also beformed by stamping aluminum plate 10 with a contact piece with a recessor hole that defines post 30 and then depositing nickel buffer layer 24and copper surface layer 26 on aluminum core 22. Furthermore, nickelbuffer layer 24 and copper surface layer 26 can be deposited on aluminumcore 22 using electroplating, chemical vapor deposition (CVD), physicalvapor deposition (PVD) and so on.

FIGS. 2A and 2B are cross-sectional views showing a method of making anadhesive in accordance with an embodiment of the present invention, andFIGS. 2C and 2D are top and bottom views, respectively, corresponding toFIG. 2B.

FIG. 2A is a cross-sectional view of adhesive 34. Adhesive 34 isillustrated as a prepreg with B-stage uncured epoxy provided as anon-solidified unpatterned sheet with a thickness of 180 microns.

Adhesive 34 can be various dielectric films or prepregs formed fromnumerous organic or inorganic electrical insulators. For instance,adhesive 34 can initially be a prepreg in which thermosetting epoxy inresin form impregnates a reinforcement and is partially cured to anintermediate stage. The epoxy can be FR-4 although other epoxies such aspolyfunctional and bismaleimide triazine (BT) are suitable. For specificapplications, cyanate esters, polyimide and PTFE are also suitable. Thereinforcement can be E-glass although other reinforcements such asS-glass, D-glass, quartz, kevlar aramid and paper are suitable. Thereinforcement can also be woven, non-woven or random microfiber. Afiller such as silica (powdered fused quartz) can be added to theprepreg to improve thermal conductivity, thermal shock resistance andthermal expansion matching. Commercially available prepregs such asSPEEDBOARD C prepreg by W.L. Gore & Associates of Eau Claire, Wisconsinare suitable.

FIGS. 2B, 2C and 2D are cross-sectional, top and bottom views,respectively, of adhesive 34 with opening 36. Opening 36 is a centralwindow that extends through adhesive 34. Opening 36 is formed bymechanical drilling through the prepreg and has a diameter of 1150microns. Opening 36 can be formed by other techniques such as punchingand stamping.

FIGS. 3A and 3B are cross-sectional views showing a method of making asubstrate in accordance with an embodiment of the present invention, andFIGS. 3C and 3D are top and bottom views, respectively, corresponding toFIG. 3B.

FIG. 3A is a cross-sectional view of substrate 40 that includesconductive layer 42 and dielectric layer 44. Conductive layer 42 is anelectrical conductor that contacts and extends above dielectric layer44, and dielectric layer 44 is an electrical insulator. For instance,conductive layer 42 is an unpatterned copper sheet with a thickness of30 microns, and dielectric layer 44 is epoxy with a thickness of 150microns.

FIGS. 3B, 3C and 3D are cross-sectional, top and bottom views,respectively, of substrate 40 with aperture 46. Aperture 46 is a centralwindow that extends through substrate 40. Aperture 46 is formed bymechanical drilling through conductive layer 42 and dielectric layer 44and has a diameter of 1150 microns. Aperture 46 can be formed with othertechniques such as punching and stamping. Preferably, opening 36 andaperture 46 have the same diameter and are formed in the same mannerwith the same drill bit at the same drilling station.

Substrate 40 is illustrated as a laminated structure. Substrate 40 canbe other electrical interconnects such as a ceramic board or a printedcircuit board. Likewise, substrate 40 can include additional layers ofembedded circuitry.

FIGS. 4A-4L are cross-sectional views showing a method of making athermal board with horizontal signal routing that includes post 30, base32, adhesive 34 and substrate 40 in accordance with an embodiment of thepresent invention, and FIGS. 4M and 4N are top and bottom views,respectively, corresponding to FIG. 4L.

FIG. 4A is a cross-sectional view of the structure with adhesive 34mounted on base 32. Adhesive 34 is mounted by lowering it onto base 32as post 30 is inserted into and through and upwards in opening 36.Adhesive 34 eventually contacts and rests on base 32. Preferably, post30 is inserted into and extends through opening 36 without contactingadhesive 34 and is aligned with and centrally located within opening 36.

FIG. 4B is a cross-sectional view of the structure with substrate 40mounted on adhesive 34. Substrate 40 is mounted by lowering it ontoadhesive 34 as post 30 is inserted into and upwards in aperture 46.Substrate 40 eventually contacts and rests on adhesive 34. Preferably,post 30 is inserted into but not through aperture 46 without contactingsubstrate 40 and is aligned with and centrally located within aperture46. As a result, gap 48 is located in aperture 46 between post 30 andsubstrate 40. Gap 48 laterally surrounds post 30 and is laterallysurrounded by substrate 40. In addition, opening 36 and aperture 46 areprecisely aligned with one another and have the same diameter.

At this stage, substrate 40 is mounted on and contacts and extends aboveadhesive 34. Post 30 extends through opening 36 into aperture 46 todielectric layer 44, is 60 microns below the top surface of conductivelayer 42 and is exposed through aperture 46 in the upward direction.Adhesive 34 contacts and is sandwiched between base 32 and substrate 40,contacts dielectric layer 44 but is spaced from conductive layer 42 andremains a non-solidified prepreg with B-stage uncured epoxy, and gap 48is filled with air.

FIG. 4C is a cross-sectional view of the structure with adhesive 34 ingap 48. Adhesive 34 is flowed into gap 48 by applying heat and pressure.In this illustration, adhesive 34 is forced into gap 48 by applyingdownward pressure to conductive layer 42 and/or upward pressure to base32, thereby moving base 32 and substrate 40 towards one another andapplying pressure to adhesive 34 while simultaneously applying heat toadhesive 34. Adhesive 34 becomes compliant enough under the heat andpressure to conform to virtually any shape. As a result, adhesive 34sandwiched between base 32 and substrate 40 is compressed, forced out ofits original shape and flows into and upward in gap 48. Base 32 andsubstrate 40 continue to move towards one another and adhesive 34eventually fills gap 48. Moreover, adhesive 34 remains sandwichedbetween and continues to fill the reduced space between base 32 andsubstrate 40.

For instance, base 32 and conductive layer 42 can be disposed betweentop and bottom platens (not shown) of a press. In addition, a top cullplate and top buffer paper (not shown) can be sandwiched betweenconductive layer 42 and the top platen, and a bottom cull plate andbottom buffer paper (not shown) can be sandwiched between base 32 andthe bottom platen. The stack includes the top platen, top cull plate,top buffer paper, substrate 40, adhesive 34, base 32, bottom bufferpaper, bottom cull plate and bottom platen in descending order.Furthermore, the stack may be positioned on the bottom platen by toolingpins (not shown) that extend upward from the bottom platen throughregistration holes (not shown) in base 32.

The platens are heated and move towards one another, thereby applyingheat and pressure to adhesive 34. The cull plates disperse the heat fromthe platens so that it is more uniformly applied to base 32 andsubstrate 40 and thus adhesive 34, and the buffer papers disperse thepressure from the platens so that it is more uniformly applied to base32 and substrate 40 and thus adhesive 34. Initially, dielectric layer 44contacts and presses down on adhesive 34. As the platen motion and heatcontinue, adhesive 34 between base 32 and substrate 40 is compressed,melted and flows into and upward in gap 48 and across dielectric layer44 to conductive layer 42. For instance, the uncured epoxy is melted bythe heat and the molten uncured epoxy is squeezed by the pressure intogap 48, however the reinforcement and the filler remain between base 32and substrate 40. Adhesive 34 elevates more rapidly than post 30 inaperture 46 and fills gap 48. Adhesive 34 also rises slightly above gap48 and overflows onto the top surfaces of post 30 and conductive layer42 adjacent to gap 48 before the platen motion stops. This may occur dueto the prepreg being slightly thicker than necessary. As a result,adhesive 34 creates a thin coating on the top surface of post 30. Theplaten motion is eventually blocked by post 30 and the platens becomestationary but continue to apply heat to adhesive 34.

The upward flow of adhesive 34 in gap 48 is shown by the thick upwardarrows, the upward motion of post 30 and base 32 relative to substrate40 is shown by the thin upward arrows, and the downward motion ofsubstrate 40 relative to post 30 and base 32 is shown by the thindownward arrows.

FIG. 4D is a cross-sectional view of the structure with adhesive 34solidified.

For instance, the platens continue to clamp post 30 and base 32 andapply heat after the platen motion stops, thereby converting the B-stagemolten uncured epoxy into C-stage cured or hardened epoxy. Thus, theepoxy is cured in a manner similar to conventional multi-layerlamination. After the epoxy is cured, the platens move away from oneanother and the structure is released from the press.

Adhesive 34 as solidified provides a secure robust mechanical bondbetween post 30 and substrate 40 as well as between base 32 andsubstrate 40. Adhesive 34 can withstand normal operating pressurewithout distortion or damage and is only temporarily distorted underunusually high pressure. Furthermore, adhesive 34 can absorb thermalexpansion mismatch between post 30 and substrate 40 and between base 32and substrate 40.

At this stage, post 30 and conductive layer 42 are essentially coplanarwith one another and adhesive 34 and conductive layer 42 extend to a topsurface that faces in the upward direction. For instance, adhesive 34between base 32 and dielectric layer 44 has a thickness of 120 micronswhich is 60 microns less than its initial thickness of 180 microns, post30 ascends 60 microns in aperture 46 and substrate 40 descends 60microns relative to post 30. The 300 micron height of post 30 isessentially the same as the combined height of conductive layer 42 (30microns), dielectric layer 44 (150 microns) and the underlying adhesive34 (120 microns). Furthermore, post 30 continues to be centrally locatedin opening 36 and aperture 46 and spaced from substrate 40, and adhesive34 fills the space between base 32 and substrate 40 and fills gap 48.For instance, gap 48 (as well as adhesive 34 between post 30 andsubstrate 40) has a width of 75 microns ((1150−1000)/2) at the topsurface of post 30. Adhesive 34 extends across dielectric layer 44 ingap 48. That is, adhesive 34 in gap 48 extends in the upward anddownward directions across the thickness of dielectric layer 44 at theouter sidewall of gap 48. Adhesive 34 also includes a thin top portionabove gap 48 that contacts the top surfaces of post 30 and conductivelayer 42 and extends above post 30 by 10 microns.

FIG. 4E is a cross-sectional view of the structure after upper portionsof post 30, adhesive 34 and conductive layer 42 are removed.

Post 30, adhesive 34 and conductive layer 42 have their upper portionsremoved by grinding. For instance, a rotating diamond sand wheel anddistilled water are applied to the top of the structure. Initially, thediamond sand wheel grinds only adhesive 34. As the grinding continues,adhesive 34 becomes thinner as its grinded surface migrates downwardly.Eventually the diamond sand wheel contacts post 30 and conductive layer42 (not necessarily at the same time), and as a result, begins to grindpost 30 and conductive layer 42 as well. As the grinding continues, post30, adhesive 34 and conductive layer 42 become thinner as their grindedsurfaces migrate downwardly. The grinding continues until the desiredthickness has been removed. Thereafter, the structure is rinsed indistilled water to remove contaminants.

The grinding removes a 25 micron thick upper portion of adhesive 34, a15 micron thick upper portion of post 30 and a 15 micron thick upperportion of conductive layer 42. The decreased thickness does notappreciably affect adhesive 34. However, it substantially reduces thethickness of conductive layer 42 from 30 microns to 15 microns. It alsosubstantially reduces the thickness of copper surface layer 26 at thetop of post 30 from 27 microns to 12 microns. However, the grinding doesnot reach aluminum core 22 or nickel buffer layer 24.

At this stage, post 30, adhesive 34 and conductive layer 42 are coplanarwith one another at a smoothed lapped lateral top surface that includescopper surface layer 26 at the top of post 30, is above and excludesaluminum core 22, nickel buffer layer 24 and dielectric layer 44 andfaces in the upward direction.

FIG. 4F is a cross-sectional view of the structure with conductive layer50 deposited on post 30, adhesive 34 and conductive layer 42.

Conductive layer 50 contacts post 30, adhesive 34 and conductive layer42 and covers them in the upward direction. For instance, the structureis dipped in an activator solution to render adhesive 34 catalytic toelectroless copper, then a first copper layer is electrolessly plated onpost 30, adhesive 34 and conductive layer 42, and then a second copperlayer is electroplated on the first copper layer. The first copper layerhas a thickness of 2 microns, the second copper layer has a thickness of13 microns, and conductive layer 50 has a thickness of 15 microns. As aresult, copper surface layer 26 at the top of post 30 essentially growsand has a thickness of 27 microns (12+15), and conductive layer 42essentially grows and has a thickness of 30 microns (15+15). Thus,conductive layer 50 serves as a cover layer for post 30 and a build-uplayer for post 30 and conductive layer 42. Post 30 and conductive layer50, and conductive layers 42 and 50 are shown as a single layer forconvenience of illustration. The boundary (shown in phantom) betweenpost 30 and conductive layer 50 and between conductive layers 42 and 50may be difficult or impossible to detect since copper is plated oncopper. However, the boundary between adhesive 34 and conductive layer50 is clear.

FIG. 4G is a cross-sectional view of the structure with etch mask 52 andcover mask 54 formed on the top and bottom surfaces, respectively, ofthe structure. Etch mask 52 and cover mask 54 are illustrated asphotoresist layers similar to photoresist layers 16 and 18,respectively. Photoresist layer 52 has a pattern that selectivelyexposes conductive layer 50, and photoresist layer 54 remainsunpatterned and covers base 32.

FIG. 4H is a cross-sectional view of the structure with selectedportions of conductive layers 42 and 50 removed by etching conductivelayers 42 and 50 in the pattern defined by etch mask 52. The wetchemical etch etches through conductive layers 42 and 50 to exposeadhesive 34 and dielectric layer 44 and converts conductive layers 42and 50 from unpatterned into patterned layers, and base 32 remainsunpatterned.

For instance, the structure can be inverted so that etch mask 52 facesdownward and cover mask 54 faces upward as a bottom spray nozzle (notshown) that faces etch mask 52 upwardly sprays the wet chemical etch onconductive layers 42 and 50 and etch mask 52 while a top spray nozzle(not shown) that faces cover mask 54 is deactivated so that gravityassists with removing the etched byproducts. Alternatively, thestructure can be dipped in the wet chemical etch since cover mask 54provides back-side protection. The wet chemical etch is highly selectiveof copper and etches through conductive layers 42 and 50 to adhesive 34and dielectric layer 44. A suitable wet chemical etch can be provided bya solution containing alkaline ammonia or a dilute mixture of nitric andhydrochloric acid. Likewise, the wet chemical etch can be acidic oralkaline. The optimal etch time for patterning conductive layers 42 and50 without excessively exposing them to the wet chemical etch can beestablished through trial and error.

FIG. 4I is a cross-sectional view of the structure after etch mask 52and cover mask 54 are removed. Photoresist layers 52 and 54 can bestripped in the same manner as photoresist layers 16 and 18.

Conductive layers 42 and 50 as etched include pad 56, routing line 58and terminal 60, and conductive layer 50 as etched includes cap 62. Pad56, routing line 58 and terminal 60 are unetched portions of conductivelayers 42 and 50 defined by etch mask 52, and cap 62 is an unetchedportion of conductive layer 50 defined by etch mask 52. Thus, conductivelayers 42 and 50 are a patterned layer that includes pad 56, routingline 58 and terminal 60 and excludes cap 62. Furthermore, routing line58 is a copper trace that contacts and extends above dielectric layer 44and is adjacent to and electrically connects pad 56 and terminal 60.

Conductive trace 64 is provided by pad 56, routing line 58 and terminal60. Similarly, an electrically conductive path between pad 56 andterminal 60 is routing line 58. Conductive trace 64 provides horizontal(lateral) fan-out routing from pad 56 to terminal 60. Conductive trace64 is not be limited to this configuration. For instance, theelectrically conductive path can include vias that extend throughdielectric layer 44 and additional routing lines (above and/or belowdielectric layer 44) as well as passive components such as resistors andcapacitors mounted on additional pads.

Heat spreader 66 includes post 30, base 32 and cap 62. Post 30 and base32 are integral with one another. Cap 62 is above and adjacent to andcovers in the upward direction and extends laterally in the lateraldirections from the top of post 30. Cap 62 is positioned so that post 30is centrally located within its periphery. Cap 62 also contacts theunderlying portion of adhesive 34 that is coplanar with and adjacent toand laterally surrounds post 30 and covers this portion in the upwarddirection.

Heat spreader 66 is essentially a heat slug with an inverted T-likeshape that includes a pedestal (post 30), wings (base 32 portions thatextend laterally from the pedestal) and a thermal pad (cap 62).

FIG. 4J is a cross-sectional view of the structure with solder mask 68formed on dielectric layer 44, conductive layer 50 and cap 62.

Solder mask 68 is an electrically insulative layer that is selectivelypatterned to expose pad 56, terminal 60 and cap 62 and cover routingline 58 and the exposed portions of adhesive 34 and dielectric layer 44in the upward direction. Solder mask 68 has a thickness of 25 micronsabove pad 56 and terminal 60 and extends 55 microns (30+25) abovedielectric layer 44.

Solder mask 68 can initially be a photoimageable liquid resin that isdispensed on the structure. Thereafter, solder mask 68 is patterned byselectively applying light through a reticle (not shown) so that thesolder mask portions exposed to the light are rendered insoluble,applying a developer solution to remove the solder mask portions thatare unexposed to the light and remain soluble and then hard baking, asis conventional.

FIG. 4K is a cross-sectional view of the structure with plated contacts70 formed on pad 56, terminal 60 and cap 62.

Plated contacts 70 are thin spot plated metal coatings that contact pad56, terminal 60 and cap 62 and cover their exposed portions in theupward direction. For instance, a nickel layer is electrolessly platedon pad 56, terminal 60 and cap 62, and then a gold layer iselectrolessly plated on the nickel layer. The buried nickel layer has athickness of 3 microns, the gold surface layer has a thickness of 0.5microns, and plated contacts 70 have a thickness of 3.5 microns.

Pad 56, terminal 60 and cap 62 treated with plated contacts 70 as asurface finish have several advantages. The buried nickel layer providesthe primary mechanical and electrical and/or thermal connection, and thegold surface layer provides a wettable surface to facilitate solderreflow. Plated contacts 70 also protect pad 56, terminal 60 and cap 62from corrosion. Plated contacts 70 can include a wide variety of metalsto accommodate the external connection media. For instance, a silversurface layer plated on a buried nickel layer can accommodate a solderjoint or a wire bond.

Pad 56, terminal 60 and cap 62 treated with plated contacts 70 are shownas single layers for convenience of illustration. The boundary (notshown) with plated contacts 70 in pad 56, terminal 60 and cap 62 occursat the copper/nickel interface.

At this stage, the manufacture of thermal board 72 can be consideredcomplete.

FIGS. 4L, 4M and 4N are cross-sectional, top and bottom views,respectively, of thermal board 72 after it is detached at peripheraledges along cut lines from a support frame and/or adjacent thermalboards in a batch.

Thermal board 72 includes adhesive 34, substrate 40, heat spreader 66and solder mask 68. Substrate 40 includes dielectric layer 44 andconductive trace 64 which includes pad 56, routing line 58 and terminal60. Heat spreader 66 includes post 30, base 32 and cap 62.

Post 30 extends through opening 36 and into aperture 46, remainscentrally located within opening 36 and aperture 46 and is coplanar withan adjacent portion of adhesive 34 above dielectric layer 44. Post 30retains its cut-off conical shape with tapered sidewalls in which itsdiameter decreases as it extends upwardly from base 32 to its flatcircular top adjacent to cap 62. Base 32 covers post 30, adhesive 34,substrate 40, cap 62, conductive trace 64 and solder mask 68 in thedownward direction and extends to the peripheral edges of thermal board72. Cap 62 is above and adjacent to and thermally connected to post 30,covers the top of post 30 in the upward direction and laterally extendsfrom the top of post 30 in the lateral directions. Cap 62 also contactsand covers in the upward direction a portion of adhesive 34 that iscoplanar with and adjacent to and laterally surrounds post 30. Cap 62 isalso coplanar with pad 56 and terminal 60.

Adhesive 34 is mounted on and extends above base 32, contacts and issandwiched between and fills the space between post 30 and dielectriclayer 44 in gap 48, contacts and is sandwiched between and fills thespace between base 32 and dielectric layer 44 outside gap 48, extendslaterally from post 30 beyond and is overlapped by terminal 60, coversbase 32 outside the periphery of post 30 in the upward direction, coverssubstrate 40 in the downward direction, covers and surrounds post 30 inthe lateral directions, is contained in and fills most of the spacebetween substrate 40 and heat spreader 66 and is solidified.

Substrate 40 is mounted on and contacts adhesive 34, extends above theunderlying adhesive 34 and extends above base 32, conductive layer 42(as well as pad 56, routing line 58 and terminal 60) contacts andextends above dielectric layer 44, and dielectric layer 44 contacts andis sandwiched between adhesive 34 and conductive layer 42.

Post 30, base 32 and cap 62 remain spaced from substrate 40. As aresult, substrate 40 and heat spreader 66 are mechanically attached andelectrically isolated from one another.

Base 32, adhesive 34, dielectric layer 44 and solder mask 68 extend tostraight vertical peripheral edges of thermal board 72 after it isdetached or singulated from a batch of identical simultaneouslymanufactured thermal boards.

Pad 56 is customized as an electrical interface for a semiconductordevice such as an LED package or a semiconductor chip that issubsequently mounted on cap 62, terminal 60 is customized as anelectrical interface for the next level assembly such as a solderablewire from a printed circuit board, cap 62 is customized as a thermalinterface for the semiconductor device, and base 32 is customized as athermal interface for the next level assembly such as a heat sink for anelectronic device. Furthermore, cap 62 is thermally connected to base 32by post 30.

Pad 56 and terminal 60 are laterally offset from one another and exposedat the top surface of thermal board 72, thereby providing horizontalfan-out routing between the semiconductor device and the next levelassembly.

Pad 56, terminal 60 and cap 62 are coplanar with one another at theirtop surfaces above dielectric layer 44.

Conductive trace 64 is shown in cross-section as a continuous circuittrace for convenience of illustration. However, conductive trace 64typically provides horizontal signal routing in both the X and Ydirections. That is, pad 56 and terminal 60 are laterally offset fromone another in the X and Y directions, and routing line 58 routes in theX and Y directions.

Heat spreader 66 provides heat spreading and heat dissipation from asemiconductor device that is subsequently mounted on cap 62 to the nextlevel assembly that thermal board 72 is subsequently mounted on. Thesemiconductor device generates heat that flows into cap 62, from cap 62into post 30 and through post 30 into base 32 where it is spread out anddissipated in the downward direction, for instance to an underlying heatsink.

Thermal board 72 does not expose post 30 or routing line 58. Post 30 iscovered by cap 62, routing line 58 is covered by solder mask 68, andadhesive 34 at its top surface is covered by cap 62 and solder mask 68.Post 30 and routing line 58 are shown in phantom in FIG. 4M forconvenience of illustration.

Thermal board 72 includes other conductive traces 64 that typicallyinclude pad 56, routing line 58 and terminal 60. A single conductivetrace 64 is described and labeled for convenience of illustration. Inconductive traces 64, pads 56 and terminals 60 generally have identicalshapes and sizes whereas routing lines 58 generally have differentrouting configurations. For instance, some conductive traces 64 may bespaced and separated and electrically isolated from one another whereasother conductive traces 64 can intersect or route to the same pad 56,routing line 58 or terminal 60 and be electrically connected to oneanother. Likewise, some pads 56 may receive independent signals whereasother pads 56 share a common signal, power or ground.

Thermal board 72 can be adapted for an LED package with blue, green andred LED chips, with each LED chip including an anode and a cathode andeach LED package including a corresponding anode terminal and cathodeterminal. In this instance, thermal board 72 can include six pads 56 andfour terminals 60 so that each anode is routed from a separate pad 56 toa separate terminal 60 whereas each cathode is routed from a separatepad 56 to a common ground terminal 60.

A brief cleaning step can be applied to the structure at variousmanufacturing stages to remove oxides and debris that may be present onthe exposed metal. For instance, a brief oxygen plasma cleaning step canbe applied to the structure. Alternatively, a brief wet chemicalcleaning step using a solution containing potassium permanganate can beapplied to the structure. Likewise, the structure can be rinsed indistilled water to remove contaminants. The cleaning step cleans thedesired surfaces without appreciably affecting or damaging thestructure.

Advantageously, there is no plating bus or related circuitry that needbe disconnected or severed from conductive traces 64 after they areformed. A plating bus can be disconnected during the wet chemical etchthat forms pad 56, routing line 58, terminal 60 and cap 62.

Thermal board 72 can include registration holes (not shown) that aredrilled or sliced through base 32, adhesive 34, substrate 40 and soldermask 68 so that thermal board 72 can be positioned by inserting toolingpins through the registration holes when it is subsequently mounted onan underlying carrier.

Thermal board 72 can omit cap 62. This can be accomplished by adjustingetch mask 52 to expose conductive layer 50 above all of aperture 46 tothe wet chemical etch that forms pad 56, routing line 58 and terminal60. This can also be accomplished by omitting conductive layer 50.

Thermal board 72 can accommodate multiple semiconductor devices ratherthan one. This can be accomplished by adjusting etch mask 16 to defineadditional posts 30, adjusting adhesive 34 to include additionalopenings 36, adjusting substrate 40 to include additional apertures 46,adjusting etch mask 52 to define additional pads 56, routing lines 58,terminals 60 and caps 62 and adjusting solder mask 68 to containadditional openings. The elements except for terminals 60 can belaterally repositioned to provide a 2×2 array for four semiconductordevices. In addition, the topography (lateral shape) can be adjusted forsome but not all of the elements. For instance, pads 56, terminals 60and caps 62 can retain the same topography whereas routing lines 58 havedifferent routing configurations.

FIGS. 5A, 5B and 5C are cross-sectional, top and bottom views,respectively, of a thermal board with vertical signal routing inaccordance with an embodiment of the present invention.

In this embodiment, the terminal is located at the bottom of the thermalboard. For purposes of brevity, any description of thermal board 72 isincorporated herein insofar as the same is applicable, and the samedescription need not be repeated Likewise, elements of the thermal boardsimilar to those in thermal board 72 have corresponding referencenumerals.

Thermal board 74 includes adhesive 34, substrate 40, conductive trace64, heat spreader 66 and solder masks 68 and 69. Substrate 40 includesdielectric layer 44. Conductive trace 64 includes pad 56, routing line58, via 59 and terminal 60. Heat spreader 66 includes post 30, base 32and cap 62.

Base 32 is thinner in this embodiment than the previous embodiment andis spaced from the peripheral edges of thermal board 74. Base 32 coverspost 30 and cap 62 but not adhesive 34, substrate 40, conductive trace64 or solder masks 68 and 69 in the downward direction. Base 32 alsosupports substrate 40 and is coplanar with terminal 60 below adhesive34.

Via 59 is an electrical conductor that extends vertically from routingline 58 through dielectric layer 44 and adhesive 34 to terminal 60.Furthermore, terminal 60 contacts and extends below adhesive 34, isspaced from and extends below substrate 40 and is spaced from andlocated between base 32 and the peripheral edges of thermal board 74.Thus, adhesive 34 extends laterally from post 30 beyond and overlapsterminal 60, via 59 is adjacent to and electrically connects routingline 58 and terminal 60, and conductive trace 64 provides vertical (topto bottom) signal routing from pad 56 to terminal 60.

Solder mask 69 is an electrically insulative layer similar to soldermask 68 that exposes base 32 and terminal 60 and covers the exposedportions of adhesive 34 in the downward direction.

Thermal board 74 can be manufactured in a manner similar to thermalboard 72 with suitable adjustments for base 32, conductive trace 64 andsolder masks 68 and 69. For instance, aluminum plate 10 has a thicknessof 330 microns (rather than 500 microns) so that base 32 has a thicknessof 60 microns (rather than 230 microns). Thereafter, adhesive 34 ismounted on base 32, substrate 40 is mounted on adhesive 34, heat andpressure are applied to flow and solidify adhesive 34, grinding isapplied to planarize the top surface and then conductive layer 50 isdeposited on the top surface as previously described. Next, a hole isdrilled downward through conductive layers 42 and 50, dielectric layer44 and adhesive 34 into but not through base 32 and then via 59 isdeposited into the hole by electroplating, screen printing or dispensingby an injection nozzle in step-and-repeat fashion. Thereafter,conductive layers 42 and 50 are etched to form pad 56 and routing line58, conductive layer 50 is etched to form cap 62 and base 32 is etchedto form terminal 60. Base 32 as etched is reduced to its central portionand terminal 60 is an unetched portion of base 32 that contacts andextends below adhesive 34, is spaced and separated from and no longer apart of base 32 and is adjacent to via 59. Thereafter, solder mask 68 isformed on the top surface to selectively expose pad 56 and cap 62,solder mask 69 is formed on the bottom surface to selectively exposebase 32 and terminal 60 and then plated contacts 70 provide a surfacefinish for pad 56, terminal 60 and cap 62.

FIGS. 6A, 6B and 6C are cross-sectional, top and bottom views,respectively, of a thermal board with a conductive trace on an adhesivein accordance with an embodiment of the present invention.

In this embodiment, the conductive trace contacts the adhesive and thedielectric layer is omitted. For purposes of brevity, any description ofthermal board 72 is incorporated herein insofar as the same isapplicable, and the same description need not be repeated. Likewise,elements of the thermal board similar to those in thermal board 72 havecorresponding reference numerals.

Thermal board 76 includes adhesive 34, conductive trace 64, heatspreader 66 and solder mask 68. Conductive trace 64 includes pad 56,routing line 58 and terminal 60. Heat spreader 66 includes post 30, base32 and cap 62.

Conductive layer 42 is thicker in this embodiment than the previousembodiment. For instance, conductive layer 42 has a thickness of 125microns (rather than 30 microns) so that it can be handled withoutwarping or wobbling. Pad 56, routing line 58 and terminal 60 aretherefore thicker and contact and overlap adhesive 34, and thermal board76 is devoid of a dielectric layer corresponding to dielectric layer 44.

Thermal board 76 can be manufactured in a manner similar to thermalboard 72 with suitable adjustments for post 30 and conductive layer 42.For instance, post 30 has a height of 200 microns (rather than 300microns) so that base 32 has a thickness of 330 microns (rather than 230microns). This can be accomplished by reducing the etch time.Thereafter, adhesive 34 is mounted on base 32, conductive layer 42 aloneis mounted on adhesive 34, heat and pressure are applied to flow andsolidify adhesive 34, grinding is applied to planarize the top surfaceand then conductive layer 50 is deposited on the top surface aspreviously described. Thereafter, conductive layers 42 and 50 are etchedto form pad 56, routing line 58 and terminal 60, conductive layer 50 isetched to form cap 62, then solder mask 68 is formed on the top surfaceto selectively expose pad 56, terminal 60 and cap 62 and then platedcontacts 70 provide a surface finish for pad 56, terminal 60 and cap 62.

FIGS. 7A, 7B and 7C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly that includes a thermalboard an LED package with backside contacts in accordance with anembodiment of the present invention.

Semiconductor chip assembly 100 includes thermal board 72, LED package102 and solder joints 104 and 106. LED package 102 includes LED chip108, submount 110, wire bond 112, electrical contact 114, thermalcontact 116 and transparent encapsulant 118. LED chip 108 includes anelectrode (not shown) electrically connected to a via (not shown) insubmount 110 by wire bond 112, thereby electrically connecting LED chip108 to electrical contact 114. LED chip 108 is mounted on and thermallyconnected to and mechanically attached to submount 110 by a die attach(not shown), thereby thermally connecting LED chip 108 to thermalcontact 116. Submount 110 is a ceramic block with low electricalconductivity and high thermal conductivity, and contacts 114 and 116 areplated on and protrude downwardly from the backside of submount 110.

LED package 102 is mounted on substrate 40 and heat spreader 66,electrically connected to substrate 40 and thermally connected to heatspreader 66. In particular, LED package 102 is mounted on pad 56 and cap62, overlaps post 30, is electrically connected to substrate 40 bysolder joint 104 and is thermally connected to heat spreader 66 bysolder joint 106. For instance, solder joint 104 contacts and issandwiched between and electrically connects and mechanically attachespad 56 and electrical contact 114, thereby electrically connecting LEDchip 108 to terminal 60. Likewise, solder joint 106 contacts and issandwiched between and thermally connects and mechanically attaches cap62 and thermal contact 116, thereby thermally connecting LED chip 108 tobase 32. Pad 56 is spot plated with nickel/gold to bond well with solderjoint 104 and is shaped and sized to match electrical contact 114,thereby improving signal transfer from substrate 40 to LED package 102Likewise, cap 62 is spot plated with nickel/gold to bond well withsolder joint 106 and is shaped and sized to match thermal contact 116,thereby improving heat transfer from LED package 102 to heat spreader66. Furthermore, post 30 is not and need not be shaped and sized tomatch thermal contact 116.

Transparent encapsulant 118 is a solid adherent electrically insulativeprotective plastic enclosure that provides environmental protection suchas moisture resistance and particle protection for LED chip 108 and wirebond 112. LED chip 108 and wire bond 112 are embedded in transparentencapsulant 118.

Semiconductor chip assembly 100 can be manufactured by depositing asolder material on pad 56 and cap 62, then placing contacts 114 and 116on the solder material over pad 56 and cap 62, respectively, and thenreflowing the solder material to provide solder joints 104 and 106.

For instance, solder paste is selectively screen printed on pad 56 andcap 62, then LED package 102 is positioned over thermal board 72 using apick-up head and an automated pattern recognition system instep-and-repeat fashion. The pick-up head places contacts 114 and 116 onthe solder paste over pad 56 and cap 62, respectively. Next, the solderpaste is heated and reflowed at a relatively low temperature such as190° C. and then the heat is removed and the solder paste cools andsolidifies to form hardened solder joints 104 and 106. Alternatively,solder balls are placed on pad 56 and cap 62, then contacts 114 and 116are placed on the solder balls over pad 56 and cap 62, respectively, andthen the solder balls are heated and reflowed to form solder joints 104and 106.

The solder material can be initially deposited on thermal board 72 orLED package 102 by plating or printing or placement techniques, thensandwiched between thermal board 72 and LED package 102 and thenreflowed. The solder material can also be deposited on terminal 60 ifrequired for the next level assembly. Furthermore, a conductive adhesivesuch as silver-filled epoxy or other connection media can be usedinstead of solder, and the connection media on pad 56, terminal 60 andcap 62 need not be the same.

Semiconductor chip assembly 100 is a second-level single-chip module.

FIGS. 8A, 8B and 8C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly that includes a thermalboard and an LED package with lateral leads in accordance with anembodiment of the present invention.

In this embodiment, the LED package has lateral leads rather thanbackside contacts. For purposes of brevity, any description of assembly100 is incorporated herein insofar as the same is applicable, and thesame description need not be repeated Likewise, elements of the assemblysimilar to those in assembly 100 have corresponding reference numeralsindexed at two-hundred rather than one-hundred. For instance, LED chip208 corresponds to LED chip 108, submount 210 corresponds to submount110, etc.

Semiconductor chip assembly 200 includes thermal board 72, LED package202 and solder joints 204 and 206. LED package 202 includes LED chip208, submount 210, wire bond 212, lead 214 and transparent encapsulant218. LED chip 208 is electrically connected to lead 214 by wire bond212. Submount 210 includes thermal contact surface 216 at its backside,is narrower than submount 110 and has the same lateral size and shape asthermal contact 116. LED chip 208 is mounted on and thermally connectedto and mechanically attached to submount 210 by a die attach (notshown), thereby thermally connecting LED chip 208 to thermal contactsurface 216. Lead 214 extends laterally from submount 210 and thermalcontact surface 216 faces downward.

LED package 202 is mounted on substrate 40 and heat spreader 66,electrically connected to substrate 40 and thermally connected to heatspreader 66. In particular, LED package 202 is mounted on pad 56 and cap62, overlaps post 30, is electrically connected to substrate 40 bysolder joint 204 and is thermally connected to heat spreader 66 bysolder joint 206. For instance, solder joint 204 contacts and issandwiched between and electrically connects and mechanically attachespad 56 and lead 214, thereby electrically connecting LED chip 208 toterminal 60. Likewise, solder joint 206 contacts and is sandwichedbetween and thermally connects and mechanically attaches cap 62 andthermal contact surface 216, thereby thermally connecting LED chip 208to base 32.

Semiconductor chip assembly 200 can be manufactured by depositing asolder material on pad 56 and cap 62, then placing lead 214 and thermalcontact surface 216 on the solder material over pad 56 and cap 62,respectively, and then reflowing the solder material to provide solderjoints 204 and 206.

Semiconductor chip assembly 200 is a second-level single-chip module.

FIGS. 9A, 9B and 9C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly that includes a thermalboard with horizontal signal routing and a semiconductor chip inaccordance with an embodiment of the present invention.

In this embodiment, the semiconductor device is a chip rather than apackage and the chip is mounted on the heat spreader but not thesubstrate. Furthermore, the chip overlaps the post but not thesubstrate, is electrically connected to the pad using a wire bond and isthermally connected to the cap using a die attach.

Semiconductor chip assembly 300 includes thermal board 72, chip 302,wire bond 304, die attach 306 and encapsulant 308. Chip 302 includes topsurface 310, bottom surface 312 and bond pad 314. Top surface 310 is theactive surface and includes bond pad 314 and bottom surface 312 is thethermal contact surface.

Chip 302 is mounted on heat spreader 66, electrically connected tosubstrate 40 and thermally connected to heat spreader 66. In particular,chip 302 is mounted on cap 62, is within the periphery of cap 62,overlaps post 30 but does not overlap substrate 40, is electricallyconnected to substrate 40 by wire bond 304 and is thermally connected toand mechanically attached to heat spreader 66 by die attach 306. Forinstance, wire bond 304 is bonded to and electrically connects pads 56and 314, thereby electrically connecting chip 302 to terminal 60.Likewise, die attach 306 contacts and is sandwiched between andthermally connects and mechanically attaches cap 62 and thermal contactsurface 312, thereby thermally connecting chip 302 to base 32. Pad 56 isspot plated with nickel/silver to bond well with wire bond 304, therebyimproving signal transfer from substrate 40 to chip 302, and cap 62 isshaped and sized to match thermal contact surface 312, thereby improvingheat transfer from chip 302 to heat spreader 66. Furthermore, post 30 isnot and need not be shaped and sized to match thermal contact surface312.

Encapsulant 308 is a solid adherent electrically insulative protectiveplastic enclosure that provides environmental protection such asmoisture resistance and particle protection for chip 302 and wire bond304. Chip 302 and wire bond 304 are embedded in encapsulant 308.Furthermore, encapsulant 308 can be transparent if chip 302 is anoptical chip such as an LED. Encapsulant 308 is transparent in FIG. 8Bfor convenience of illustration.

Semiconductor chip assembly 300 can be manufactured by mounting chip 302on cap 62 using die attach 306, then wire bonding pads 56 and 314 andthen forming encapsulant 308.

For instance, die attach 306 is initially a silver-filled epoxy pastewith high thermal conductivity that is selectively screen printed on cap62 and then chip 302 placed on the epoxy paste using a pick-up head andan automated pattern recognition system in step-and-repeat fashion.Thereafter, the epoxy paste is heated and hardened at a relatively lowtemperature such as 190° C. to form die attach 306. Next, wire bond 304is a gold wire that is thermosonically ball bonded to pads 56 and 314and then encapsulant 308 is transfer molded on the structure.

Chip 302 can be electrically connected to pad 56 by a wide variety ofconnection media, thermally connected to and mechanically attached toheat spreader 66 by a wide variety of thermal adhesives and encapsulatedby a wide variety of encapsulants.

Semiconductor chip assembly 300 is a first-level single-chip package.

FIGS. 10A, 10B and 10C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly that includes a thermalboard with vertical signal routing and a semiconductor chip inaccordance with an embodiment of the present invention.

Semiconductor chip assembly 400 includes thermal board 74, chip 402,wire bond 404, die attach 406 and encapsulant 408. Chip 402 includes topsurface 410, bottom surface 412 and bond pad 414.

FIGS. 11A, 11B and 11C are cross-sectional, top and bottom views,respectively, of a light source subassembly that includes asemiconductor chip assembly and a heat sink in accordance with anembodiment of the present invention.

Light source subassembly 500 includes semiconductor chip assembly 100and heat sink 502. Heat sink 502 includes thermal contact surface 504,fins 506 and fan 508. Assembly 100 is mounted on heat sink 502 andmechanically fastened to heat sink 502, for instance by screws (notshown). As a result, base 32 is clamped against and thermally connectedto thermal contact surface 504, thereby thermally connecting heatspreader 66 to heat sink 502. Heat spreader 66 spreads the heat from LEDchip 108 and transfers the spread heat to heat sink 502, which in turndissipates the heat into the exterior environment using fins 506 and fan508.

Light source subassembly 500 is designed for a light fixture (not shown)that is interchangeable with a standard incandescent light bulb. Thelight fixture includes subassembly 500, a glass cap, a threaded base, acontrol board, wiring and a housing. Subassembly 500, the control boardand the wiring are enclosed within the housing. The wiring extends fromthe control board and is soldered to terminals 60. The glass cap and thethreaded base protrude from opposite ends of the housing. The glass capexposes LED chip 108, the threaded base is configured to screw into alight socket and the control board is electrically connected toterminals 60 by the wiring. The housing is a two-piece plastic shellwith top and bottom pieces. The glass cap is attached to and protrudesabove the top piece, the threaded base is attached to and protrudesbelow the bottom piece, and subassembly 500 and the control board aremounted on the bottom piece and extend into the top piece.

During operation, the threaded base transfers AC from a light socket tothe control board, which converts the AC to modulated DC and the wiringtransmits the modulated DC to terminal 60 and grounds another terminal60. As a result, LED chip 108 illuminates bright light through the glasscap. LED chip 108 also generates intense localized heat that flows intoand is spread by heat spreader 66 and flows from heat spreader 66 intoheat sink 502 where fins 506 heat the air, and fan 508 blows the hot airradially outward through slots in the housing into the externalenvironment.

The semiconductor chip assemblies and thermal boards described above aremerely exemplary. Numerous other embodiments are contemplated. Inaddition, the embodiments described above can be mixed-and-matched withone another and with other embodiments depending on design andreliability considerations. For instance, the semiconductor device canbe an LED package and the thermal board can provide vertical signalrouting. The substrate can include single-level conductive traces andmulti-level conductive traces. The thermal board can include multipleposts arranged in an array for multiple semiconductor devices and caninclude additional conductive traces to accommodate the additionalsemiconductor devices. Likewise, the semiconductor device can be an LEDpackage with multiple LED chips and the thermal board can includeadditional conductive traces to accommodate the additional LED chips.The semiconductor device and the cap can overlap the substrate and coverthe post, the aperture and the opening in the upward direction.

The semiconductor device can share or not share the heat spreader withother semiconductor devices. For instance, a single semiconductor devicecan be mounted on the heat spreader. Alternatively, numeroussemiconductor devices can mounted on the heat spreader. For instance,four small chips in a 2×2 array can be attached to the post and thesubstrate can include additional conductive traces to receive and routeadditional wire bonds to the chips. This may be more cost effective thanproviding a miniature post for each chip.

The semiconductor chip can be optical or non-optical. For instance, thechip can be an LED, a solar cell, a microprocessor, a controller or anRF power amplifier. Likewise, the semiconductor package can be an LEDpackage or an RF module. Thus, the semiconductor device can be apackaged or unpackaged optical or non-optical chip. Furthermore, thesemiconductor device can be mechanically, electrically and thermallyconnected to the thermal board using a wide variety of connection mediaincluding solder and electrically and/or thermally conductive adhesive.

The heat spreader can provide rapid, efficient and essentially uniformheat spreading and dissipation for the semiconductor device to the nextlevel assembly without heat flow through the adhesive, the substrate orelsewhere in the thermal board. As a result, the adhesive can have lowthermal conductivity which drastically reduces cost. The heat spreadercan include a post and base that are integral with one another and a capthat is metallurgically bonded and thermally connected to the post,thereby enhancing reliability and reducing cost. The cap can be coplanarwith the pad, thereby facilitating the electrical, thermal andmechanical connections with the semiconductor device. Furthermore, thecap can be customized for the semiconductor device and the base can becustomized for the next level assembly, thereby enhancing the thermalconnection from the semiconductor device to the next level assembly. Forinstance, the post can have a circular shape in a lateral plane and thecap can have a square or rectangular shape in a lateral plane with thesame or similar topography as the thermal contact of the semiconductordevice.

The heat spreader can be electrically connected to or isolated from thesemiconductor device and the substrate. For instance, the secondconductive layer on the grinded surface can include a routing line thatextends across the adhesive between the substrate and the cap andelectrically connects the semiconductor device to the heat spreader.Thereafter, the heat spreader can be electrically connected to ground,thereby electrically connecting the semiconductor device to ground.

The heat spreader can be copper/nickel/aluminum or other thermallyconductive metallic structures.

The post can be deposited on or integral with the base. The post can beintegral with the base when they share single-piece metals at theirinterface such as a copper coating on a nickel buffer layer on analuminum core.

The post can include a flat top surface that is coplanar with theadhesive. For instance, the post can be coplanar with the adhesive orthe post can be etched after the adhesive is solidified to provide acavity in the adhesive over the post. The post can also be selectivelyetched to provide a cavity in the post that extends below its topsurface. In any case, the semiconductor device can be mounted on thepost and located in the cavity, and the wire bond can extend from thesemiconductor device in the cavity to the pad outside the cavity. Inthis instance, the semiconductor device can be an LED chip and thecavity can focus the LED light in the upward direction.

The base can provide mechanical support for the substrate. For instance,the base can prevent the substrate from warping during metal grinding,chip mounting, wire bonding and encapsulant molding. The base can alsocover the assembly in the downward direction when the terminal is abovethe dielectric layer, or alternatively, be spaced from the peripheraledges of the assembly when the terminal is below the adhesive.Furthermore, the base can include fins at its backside that protrude inthe downward direction. For instance, the base can be cut at its bottomsurface by a routing machine to form lateral grooves that define thefins. In this instance, the base can have a thickness of 700 microns,the grooves can have a depth of 500 microns and the fins can have aheight of 500 microns. The fins can increase the surface area of thebase, thereby increasing the thermal conductivity of the base by thermalconvection when it remains exposed to the air rather than mounted on aheat sink.

The cap can be formed by numerous deposition techniques includingelectroplating, electroless plating, evaporating and sputtering as asingle layer or multiple layers after the adhesive is solidified, eitherbefore, during or after the pad and/or the terminal is formed. The capcan be the same metal as the post or the adjacent top of the post.Furthermore, the cap can extend across the aperture to the substrate orreside within the periphery of the aperture. Thus, the cap may contactor be spaced from the substrate. In any case, the cap extends laterallyfrom the top of the post in the lateral directions.

The adhesive can provide a robust mechanical bond between the heatspreader and the substrate. For instance, the adhesive can extendlaterally from the post beyond the conductive trace to the peripheraledges of the assembly, the adhesive can fill the space between the heatspreader and the substrate, the adhesive can be located in this spaceand the adhesive can be void-free with consistent bond lines. Theadhesive can also absorb thermal expansion mismatch between the heatspreader and the substrate. Furthermore, the adhesive can be a low costdielectric that need not have high thermal conductivity. Moreover, theadhesive is not prone to delamination.

The adhesive thickness can be adjusted so that the adhesive essentiallyfills the gap and essentially all the adhesive is within structure onceit is solidified and/or grinded. For instance, the optimal prepregthickness can be established through trial and error Likewise, thedielectric layer thickness can be adjusted to achieve this result.

The substrate can be a low cost laminated structure that need not havehigh thermal conductivity. Furthermore, the substrate can include asingle conductive layer or multiple conductive layers. Moreover, thesubstrate can include or consist of the conductive layer.

The conductive layer alone can be mounted on the adhesive. For instance,the aperture can be formed in the conductive layer and then theconductive layer and nothing else can be mounted on the adhesive so thatthe conductive layer contacts the adhesive and is exposed in the upwarddirection and the post extends into and is exposed in the upwarddirection by the aperture. In this instance, the conductive layer canhave a thickness of 100 to 200 microns such as 125 microns which isthick enough to handle without warping and wobbling and to accommodatehigh drive current yet thin enough to pattern without excessive etching.

The conductive layer and the dielectric layer can be mounted on theadhesive. For instance, the conductive layer can be laminated on thedielectric layer, then the aperture can be formed in the conductivelayer and the dielectric layer, and then the conductive layer and thedielectric layer can be mounted on the adhesive so that the conductivelayer is exposed in the upward direction, the dielectric layer contactsand is sandwiched between and separates the conductive layer and theadhesive and the post extends into and is exposed in the upwarddirection by the aperture. In this instance, the conductive layer canhave a thickness of 10 to 50 microns such as 30 microns which is thickenough for reliable signal transfer yet thin enough to reduce weight andcost. Furthermore, the dielectric layer is a permanent part of thethermal board.

The conductive layer and a carrier can be mounted on the adhesive. Forinstance, the conductive layer can be attached to a carrier suchbiaxially-oriented polyethylene terephthalate polyester (Mylar) by athin film, then the aperture can be formed in the conductive layer butnot the carrier, then the conductive layer and the carrier can bemounted on the adhesive so that the carrier covers the conductive layerand is exposed in the upward direction, the thin film contacts and issandwiched between the carrier and the conductive layer, the conductivelayer contacts and is sandwiched between the thin film and the adhesive,and the post is aligned with the aperture and covered in the upwarddirection by the carrier. After the adhesive is solidified, the thinfilm can be decomposed by UV light so that the carrier can be peeled offthe conductive layer, thereby exposing the conductive layer in theupward direction, and then the conductive layer can be grinded andpatterned to provide the conductive trace. In this instance, theconductive layer can have a thickness of 10 to 50 microns such as 30microns which is thick enough for reliable signal transfer yet thinenough to reduce weight and cost, and the carrier can have a thicknessof 300 to 500 microns which is thick enough to handle without warpingand wobbling yet thin enough to reduce weight and cost. Furthermore, thecarrier is a temporary fixture and not a permanent part of the thermalboard.

The pad and the terminal can have a wide variety of packaging formats asrequired by the semiconductor device and the next level assembly.

The pad and the cap can be coplanar at their top surfaces, therebyenhancing solder joints between the semiconductor device and the thermalboard by controlling solder ball collapse.

The pad, the terminal and the routing line over the dielectric layer canbe formed by numerous deposition techniques including electroplating,electroless plating, evaporating and sputtering as a single layer ormultiple layers, either before or after the substrate is mounted on theadhesive. For instance, the conductive layer can be patterned on thesubstrate before it is mounted on the adhesive or after it is attachedto the post and the base by the adhesive.

The plated contact surface finish can be formed before or after the padand the terminal are formed. For instance, the plated layer can bedeposited on the second conductive layer and then patterned using theetch mask that defines the pad and the terminal.

The conductive trace can include additional pads, terminals, vias androuting lines as well as passive components and have differentconfigurations. The conductive trace can function as a signal, power orground layer depending on the purpose of the corresponding semiconductordevice pad. The conductive trace can also include various conductivemetals such as copper, gold, nickel, silver, palladium, tin,combinations thereof, and alloys thereof. The preferred composition willdepend on the nature of the external connection media as well as designand reliability considerations.

Those skilled in the art will understand that in the context of asemiconductor chip assembly, the copper material can be pure elementalcopper but is typically a copper alloy that is mostly copper such ascopper-zirconium (99.9% copper), copper-silver-phosphorus-magnesium(99.7% copper) and copper-tin-iron-phosphorus (99.7% copper) to improvemechanical properties such as tensile strength and elongation. Thoseskilled in the art will also understand that in the context of asemiconductor chip assembly, the aluminum material can be pure elementalaluminum but is typically an aluminum alloy that is mostly aluminum suchas aluminum alloy 5052 (aluminum (˜97%), magnesium (2.2-2.8%) and othertrace elements such as silicon, iron, chromium or copper (<0.5%)) andaluminum alloy 6061 (aluminum (˜97%), magnesium (0.18-1.2%), silicon(0.5-0.8%) and other trace elements such as iron, copper, titanium ormagnesium (<0.5%)). Those skilled in the art will further understandthat in the context of a semiconductor chip assembly, the nickelmaterial can be pure elemental nickel but is typically a nickel alloysuch as nickel-phosphorous (92-99.5% nickel).

The cap, dielectric layer, solder mask, plated contacts and secondconductive layer on the grinded surface are generally desirable but maybe omitted in some embodiments. For instance, if the opening andaperture are punched rather than drilled so that the top of the post isshaped and sized to accommodate a thermal contact surface of thesemiconductor device then the cap and the second conductive layer may beomitted to reduce cost. Likewise, if single-level signal routing is usedthen the dielectric layer may be omitted to reduce cost.

The thermal board can include a thermal via that is spaced from thepost, extends through the dielectric layer and the adhesive outside theopening and the aperture and is adjacent to and thermally connects thebase and the cap to improve heat dissipation from the cap to the baseand heat spreading in the base.

The assembly can provide horizontal or vertical single-level ormulti-level signal routing.

Horizontal single-level signal routing with the pad, the terminal andthe routing line above the dielectric layer is disclosed in U.S.application Ser. No. 12/616,773 filed Nov. 11, 2009 by Charles W. C. Linet al. entitled “Semiconductor Chip Assembly with Post/Base HeatSpreader and Substrate” which is incorporated by reference.

Horizontal single-level signal routing with the pad, the terminal andthe routing line above the adhesive and no dielectric layer is disclosedin U.S. application Ser. No. 12/616,775 filed Nov. 11, 2009 by CharlesW. C. Lin et al. entitled “Semiconductor Chip Assembly with Post/BaseHeat Spreader and Conductive Trace” which is incorporated by reference.

Horizontal multi-level signal routing with the pad and the terminalabove the dielectric layer electrically connected by first and secondvias through the dielectric layer and a routing line beneath thedielectric layer is disclosed in U.S. application Ser. No. 12/557,540filed Sep. 11, 2009 by Chia-Chung Wang et al. entitled “SemiconductorChip Assembly with Post/Base Heat Spreader and Horizontal SignalRouting” which is incorporated by reference.

Vertical multi-level signal routing with the pad above the dielectriclayer and the terminal beneath the adhesive electrically connected by afirst via through the dielectric layer, a routing line beneath thedielectric layer and a second via through the adhesive is disclosed inU.S. application Ser. No. 12/557,541 filed Sep. 11, 2009 by Chia-ChungWang et al. entitled “Semiconductor Chip Assembly with Post/Base HeatSpreader and Vertical Signal Routing” which is incorporated byreference.

The working format for the thermal board can be a single thermal boardor multiple thermal boards based on the manufacturing design. Forinstance, a single thermal board can be manufactured individually.Alternatively, numerous thermal boards can be simultaneously batchmanufactured using a single copper/nickel/aluminum carrier, a singleadhesive, a single substrate and a single solder mask and then separatedfrom one another. Likewise, numerous sets of heat spreaders andconductive traces that are each dedicated to a single semiconductordevice can be simultaneously batch manufactured for each thermal boardin the batch using a single copper/nickel/aluminum carrier, a singleadhesive, a single substrate and a single solder mask.

For example, multiple recesses can be etched in the aluminum plate toform the aluminum core for multiple posts and the base, then the nickelbuffer layer can be plated on the aluminum core, then the copper surfacelayer can be plated on the nickel buffer layer, then the non-solidifiedadhesive with openings corresponding to the posts can be mounted on thebase such that each post extends through an opening, then the substrate(with a single conductive layer, a single dielectric layer and aperturescorresponding to the posts) can be mounted on the adhesive such thateach post extends through an opening into an aperture, then the base andthe substrate can be moved towards one another by platens to force theadhesive into the gaps in the apertures between the posts and thesubstrate, then the adhesive can be cured and solidified, then theposts, the adhesive and the first conductive layer can be grinded toform a lateral top surface, then the second conductive layer can beplated on the posts, the adhesive and the first conductive layer, thenthe first and second conductive layers can be etched to form the padsand the terminals corresponding to the posts and the second conductivelayer can be etched to form the caps corresponding to the posts, thenthe solder mask can be deposited on the structure and patterned toexpose the pads, the terminals and the caps, then the plated contactsurface finish can be formed on the pads, the terminals and the caps andthen the base, the substrate, the adhesive and the solder mask can becut or cracked at the desired locations of the peripheral edges of thethermal boards, thereby separating the individual thermal boards fromone another.

The working format for the semiconductor chip assembly can be a singleassembly or multiple assemblies based on the manufacturing design. Forinstance, a single assembly can be manufactured individually.Alternatively, numerous assemblies can be simultaneously batchmanufactured before the thermal boards are separated from one another.Likewise, multiple semiconductor devices can be electrically, thermallyand mechanically connected to each thermal board in the batch.

For example, solder paste portions can be deposited on the pads and thecaps, then the LED packages can be placed on the solder paste portions,then the solder paste portions can be simultaneously heated, reflowedand hardened to provide the solder joints, and then the thermal boardscan be separated from one another.

As another example, die attach paste portions can be deposited on thecaps, then the chips can be placed on the die attach paste portions,then the die attach paste portions can be simultaneously heated andhardened to provide the die attaches, then the chips can be wired bondedto the corresponding pads, then the encapsulant can be formed over thechips and the wire bonds, and then the thermal boards can be separatedfrom one another.

The thermal boards can be detached from one another in a single step ormultiple steps. For instance, the thermal boards can be batchmanufactured as a panel, then the semiconductor devices can be mountedon the panel and then the semiconductor chip assemblies of the panel canbe detached from one another. Alternatively, the thermal boards can bebatch manufactured as a panel, then the thermal boards of the panel canbe singulated into strips of multiple thermal boards, then thesemiconductor devices can be mounted on the thermal boards of a stripand then the semiconductor chip assemblies of the strip can be detachedfrom one another. Furthermore, the thermal boards can be detached bymechanical sawing, laser sawing, cleaving or other suitable techniques.

The term “adjacent” refers to elements that are integral (single-piece)or in contact (not spaced or separated from) with one another. Forinstance, the post is adjacent to the base regardless of whether thepost is formed additively or subtractively.

The term “overlap” refers to above and extending within a periphery ofan underlying element. Overlap includes extending inside and outside theperiphery or residing within the periphery. For instance, thesemiconductor device overlaps the post since an imaginary vertical lineintersects the semiconductor device and the post, regardless of whetheranother element such as the cap is between the semiconductor device andthe post and is intersected by the line, and regardless of whetheranother imaginary vertical line intersects the semiconductor device butnot the post (outside the periphery of the post). Likewise, the adhesiveoverlaps the base and is overlapped by the pad, and the base isoverlapped by the post. Likewise, the post overlaps and is within aperiphery of the base. Moreover, overlap is synonymous with over andoverlapped by is synonymous with under or beneath.

The term “contact” refers to direct contact. For instance, thedielectric layer contacts the pad but does not contact the post or thebase.

The term “cover” refers to complete coverage in the upward, downwardand/or lateral directions. For instance, the base covers the post in thedownward direction but the post does not cover the base in the upwarddirection.

The term “layer” refers to patterned and unpatterned layers. Forinstance, the conductive layer can be an unpatterned blanket sheet onthe dielectric layer when the substrate is mounted on the adhesive, andthe conductive layer can be a patterned circuit with spaced traces onthe dielectric layer when the semiconductor device is mounted on theheat spreader. Furthermore, a layer can include stacked layers.

The term “pad” in conjunction with the conductive trace refers to aconnection region that is adapted to contact and/or bond to externalconnection media (such as solder or a wire bond) that electricallyconnects the conductive trace to the semiconductor device.

The term “terminal” in conjunction with the conductive trace refers to aconnection region that is adapted to contact and/or bond to externalconnection media (such as solder or a wire bond) that electricallyconnects the conductive trace to an external device (such as a PCB or awire thereto) associated with the next level assembly.

The term “cap” in conjunction with the heat spreader refers to a contactregion that is adapted to contact and/or bond to external connectionmedia (such as solder or thermally conductive adhesive) that thermallyconnects the heat spreader to the semiconductor device.

The terms “opening” and “aperture” refer to a through-hole and aresynonymous. For instance, the post is exposed by the adhesive in theupward direction when it is inserted into the opening in the adhesiveLikewise, the post is exposed by the substrate in the upward directionwhen it is inserted into the aperture in the substrate.

The term “inserted” refers to relative motion between elements. Forinstance, the post is inserted into the aperture regardless of whetherthe post is stationary and the substrate moves towards the base, thesubstrate is stationary and the post moves towards the substrate or thepost and the substrate both approach the other. Furthermore, the post isinserted (or extends) into the aperture regardless of whether it goesthrough (enters and exits) or does not go through (enters withoutexiting) the aperture.

The phrase “move towards one another” also refers to relative motionbetween elements. For instance, the base and the substrate move towardsone another regardless of whether the base is stationary and thesubstrate moves towards the base, the substrate is stationary and thebase moves towards the substrate or the base and the substrate bothapproach the other.

The phrase “aligned with” refers to relative position between elements.For instance, the post is aligned with the aperture when the adhesive ismounted on the base, the substrate is mounted on the adhesive, the postis inserted into and aligned with the opening and the aperture isaligned with the opening regardless of whether the post is inserted intothe aperture or is below and spaced from the aperture.

The phrase “mounted on” includes contact and non-contact with a singleor multiple support element(s). For instance, the semiconductor deviceis mounted on the heat spreader regardless of whether it contacts theheat spreader or is separated from the heat spreader by a die attach.Likewise, the semiconductor device is mounted on the heat spreaderregardless of whether it is mounted on the heat spreader alone or theheat spreader and the substrate.

The phrase “adhesive . . . in the gap” refers to the adhesive in thegap. For instance, adhesive that extends across the dielectric layer inthe gap refers to the adhesive in the gap that extends across thedielectric layer. Likewise, adhesive that contacts and is sandwichedbetween the post and the dielectric layer in the gap refers to theadhesive in the gap that contacts and is sandwiched between the post atthe inner sidewall of the gap and the dielectric layer at the outersidewall of the gap.

The term “above” refers to upward extension and includes adjacent andnon-adjacent elements as well as overlapping and non-overlappingelements. For instance, the post extends above, is adjacent to, overlapsand protrudes from the base. Likewise, the post extends above thedielectric layer even though it is not adjacent to or overlap thedielectric layer.

The term “below” refers to downward extension and includes adjacent andnon-adjacent elements as well as overlapping and non-overlappingelements. For instance, the base extends below, is adjacent to, isoverlapped by and protrudes from the post. Likewise, the post extendsbelow the dielectric layer even though it is not adjacent to oroverlapped by the dielectric layer.

The “upward” and “downward” vertical directions do not depend on theorientation of the semiconductor chip assembly (or the thermal board),as will be readily apparent to those skilled in the art. For instance,the post extends vertically above the base in the upward direction andthe adhesive extends vertically below the pad in the downward directionregardless of whether the assembly is inverted and/or mounted on a heatsink Likewise, the base extends “laterally” from the post in a lateralplane regardless of whether the assembly is inverted, rotated orslanted. Thus, the upward and downward directions are opposite oneanother and orthogonal to the lateral directions, and laterally alignedelements are coplanar with one another at a lateral plane orthogonal tothe upward and downward directions.

The semiconductor chip assembly of the present invention has numerousadvantages. The assembly is reliable, inexpensive and well-suited forhigh volume manufacture. The assembly is especially well-suited for highpower semiconductor devices such as LED packages and large semiconductorchips as well as multiple semiconductor devices such as smallsemiconductor chips in arrays which generate considerable heat andrequire excellent heat dissipation in order to operate effectively andreliably.

The manufacturing process is highly versatile and permits a wide varietyof mature electrical, thermal and mechanical connection technologies tobe used in a unique and improved manner. The manufacturing process canalso be performed without expensive tooling. As a result, themanufacturing process significantly enhances throughput, yield,performance and cost effectiveness compared to conventional packagingtechniques. Moreover, the assembly is well-suited for copper chip andlead-free environmental requirements.

The embodiments described herein are exemplary and may simplify or omitelements or steps well-known to those skilled in the art to preventobscuring the present invention. Likewise, the drawings may omitduplicative or unnecessary elements and reference labels to improveclarity.

Various changes and modifications to the embodiments described hereinwill be apparent to those skilled in the art. For instance, thematerials, dimensions, shapes, sizes, steps and arrangement of stepsdescribed above are merely exemplary. Such changes, modifications andequivalents may be made without departing from the spirit and scope ofthe present invention as defined in the appended claims.

1. A method of making a semiconductor chip assembly, comprising:providing a post, a base, an adhesive and a conductive layer, whereinthe post is adjacent to the base, extends above the base in an upwarddirection, extends into an opening in the adhesive and is aligned withan aperture in the conductive layer, the base extends below the post ina downward direction opposite the upward direction and extends laterallyfrom the post in lateral directions orthogonal to the upward anddownward directions, the post and the base include a copper surfacelayer and an aluminum core, the copper surface layer conformally coatsand extends above the aluminum core, and the aluminum core of the postextends above the copper surface layer of the base, the adhesive ismounted on and extends above the base, is sandwiched between the baseand the conductive layer and is non-solidified, and the conductive layeris mounted on and extends above the adhesive; then flowing the adhesiveinto and upward in a gap located in the aperture between the post andthe conductive layer; solidifying the adhesive; then providing aconductive trace that includes a pad, a terminal and a selected portionof the conductive layer; providing a heat spreader that includes thepost and the base, wherein providing the heat spreader includes grindingthe post, the adhesive and the conductive layer such that the post, theadhesive and the conductive layer are laterally aligned with one anotherat a top lateral surface that includes the copper surface layer,excludes the aluminum core and faces in the upward direction; mounting asemiconductor device on the heat spreader, wherein the semiconductordevice overlaps the post; electrically connecting the semiconductordevice to the pad, thereby electrically connecting the semiconductordevice to the terminal; and thermally connecting the semiconductordevice to the post, thereby thermally connecting the semiconductordevice to the base.
 2. The method of claim 1, wherein providing the postand the base includes: providing an aluminum plate; forming an etch maskon the aluminum plate that selectively exposes the aluminum plate;etching the aluminum plate in a pattern defined by the etch mask,thereby forming a recess in the aluminum plate that extends into but notthrough the aluminum plate; then removing the etch mask, wherein thealuminum core of the post is an unetched portion of the aluminum platethat is laterally surrounded by the recess, and the aluminum core of thebase is an unetched portion of the aluminum plate below the recess; andthen depositing the copper surface layer over the aluminum core.
 3. Themethod of claim 1, wherein: providing the adhesive includes providing aprepreg with uncured epoxy; flowing the adhesive includes melting theuncured epoxy and compressing the uncured epoxy between the base and theconductive layer; and solidifying the adhesive includes curing theuncured epoxy.
 4. The method of claim 1, wherein flowing the adhesiveincludes filling the gap with the adhesive.
 5. The method of claim 1,wherein mounting the conductive layer includes mounting the conductivelayer alone on the adhesive.
 6. The method of claim 1, wherein: mountingthe conductive layer includes mounting the conductive layer and acarrier on the adhesive, wherein the carrier is attached to and overlapsthe conductive layer and the conductive layer contacts the adhesive andis sandwiched between the adhesive and the carrier; then solidifying theadhesive; then removing the carrier; and then providing the conductivetrace.
 7. The method of claim 1, wherein providing the pad includesremoving selected portions of the conductive layer after solidifying theadhesive.
 8. The method of claim 1, wherein providing the heat spreaderincludes providing a cap that extends above and is adjacent to andcovers in the upward direction and extends laterally in the lateraldirections from a top of the post and that overlaps and is adjacent tothe adhesive after grinding the post, the adhesive and the conductivelayer and before mounting the semiconductor device.
 9. The method ofclaim 1, wherein mounting the semiconductor device includes providing afirst solder joint between the semiconductor device and the pad and asecond solder joint between the semiconductor device and the heatspreader, electrically connecting the semiconductor device includesproviding the first solder joint between the semiconductor device andthe pad, and thermally connecting the semiconductor device includesproviding the second solder joint between the semiconductor device andthe heat spreader.
 10. The method of claim 1, wherein mounting thesemiconductor device includes providing a die attach between thesemiconductor device and the heat spreader, electrically connecting thesemiconductor device includes providing a wire bond between thesemiconductor device and the pad, and thermally connecting thesemiconductor device includes providing the die attach between thesemiconductor device and the heat spreader.
 11. A method of making asemiconductor chip assembly, comprising: providing a post and a base,wherein the post is adjacent to and integral with the base and extendsabove the base in an upward direction, the base extends below the postin a downward direction opposite the upward direction and extendslaterally from the post in lateral directions orthogonal to the upwardand downward directions, the post and the base include a copper surfacelayer and an aluminum core, the copper surface layer conformally coatsand extends above the aluminum core, and the aluminum core of the postextends above the copper surface layer of the base, and providing thepost and the base includes: providing an aluminum plate; forming an etchmask on the aluminum plate that selectively exposes the aluminum plate;etching the aluminum plate in a pattern defined by the etch mask,thereby forming a recess in the aluminum plate that extends into but notthrough the aluminum plate; then removing the etch mask, wherein thealuminum core of the post is an unetched portion of the aluminum platethat is laterally surrounded by the recess, and the aluminum core of thebase is an unetched portion of the aluminum plate below the recess; thenelectrolessly plating a nickel buffer layer on the aluminum core;electrolessly plating a first copper layer on the nickel buffer layer;and electroplating a second copper layer on the first copper layer,wherein the copper surface layer includes the first and second copperlayers; providing an adhesive, wherein an opening extends through theadhesive; providing a conductive layer, wherein an aperture extendsthrough the conductive layer; mounting the adhesive on the base,including inserting the post into the opening, wherein the adhesiveextends above the base and the post extends through the opening;mounting the conductive layer on the adhesive, including aligning thepost with the aperture, wherein the conductive layer extends above theadhesive and the adhesive is sandwiched between the base and theconductive layer and is non-solidified; then applying heat to melt theadhesive; moving the base and the conductive layer towards one another,thereby moving the post upward in the aperture and applying pressure tothe molten adhesive between the base and the conductive layer, whereinthe pressure forces the molten adhesive to flow into and upward in a gaplocated in the aperture between the post and the conductive layer;applying heat to solidify the molten adhesive, thereby mechanicallyattaching the post and the base to the conductive layer; then providinga conductive trace that includes a pad and a terminal, wherein theconductive trace includes selected portions of the conductive layer andan electrically conductive path is between the pad and the terminal;mounting a semiconductor device on a heat spreader that includes thepost and the base, wherein the semiconductor device overlaps the post;electrically connecting the semiconductor device to the pad, therebyelectrically connecting the semiconductor device to the terminal; andthermally connecting the semiconductor device to the post, therebythermally connecting the semiconductor device to the base.
 12. Themethod of claim 11, wherein: providing the adhesive includes providing aprepreg with uncured epoxy; flowing the adhesive includes melting theuncured epoxy and compressing the uncured epoxy between the base and theconductive layer; and solidifying the adhesive includes curing theuncured epoxy.
 13. The method of claim 11, wherein providing the pad andthe terminal includes removing selected portions of the conductive layerusing a second etch mask that defines the pad and the terminal aftersolidifying the adhesive.
 14. The method of claim 11, wherein providingthe pad includes removing selected portions of the conductive layerusing a second etch mask that defines the pad after solidifying theadhesive, and providing the terminal includes removing selected portionsof the base using a third etch mask that defines the terminal aftersolidifying the adhesive.
 15. The method of claim 11, wherein providingthe heat spreader includes providing a cap that extends above and isadjacent to and covers in the upward direction and extends laterally inthe lateral directions from a top of the post and that overlaps and isadjacent to the adhesive using a second etch mask after solidifying theadhesive and before mounting the semiconductor device.
 16. A method ofmaking a semiconductor chip assembly, comprising: providing a post and abase, wherein the post is adjacent to and integral with the base andextends above the base in an upward direction, the base extends belowthe post in a downward direction opposite the upward direction andextends laterally from the post in lateral directions orthogonal to theupward and downward directions, the post and the base include a coppersurface layer, a nickel buffer layer and an aluminum core, the coppersurface layer conformally coats and extends above the aluminum core, thealuminum core of the post extends above the copper surface layer of thebase and the nickel buffer layer contacts and is sandwiched between andseparates the copper surface layer and the aluminum core; providing anadhesive, wherein an opening extends through the adhesive; providing aconductive layer, wherein an aperture extends through the conductivelayer; mounting the adhesive on the base, including inserting the postthrough the opening, wherein the adhesive extends above the base and thepost extends through the opening; mounting the conductive layer alone onthe adhesive, including inserting the post into the aperture, whereinthe conductive layer extends above the adhesive, the post extendsthrough the opening into the aperture, the adhesive is sandwichedbetween the base and the first conductive layer and is non-solidified,and a gap is located in the aperture between the post and the conductivelayer; then applying heat to melt the adhesive; moving the base and theconductive layer towards one another, thereby moving the post upward inthe aperture and applying pressure to the molten adhesive between thebase and the conductive layer, wherein the pressure forces the moltenadhesive to flow into and upward in the gap; applying heat to solidifythe molten adhesive, thereby mechanically attaching the post and thebase to the conductive layer; then grinding the post, the adhesive andthe conductive layer such that the post, the adhesive and the conductivelayer are laterally aligned with one another at a top lateral surfacethat includes the copper surface layer, excludes the nickel buffer layerand the aluminum core and faces in the upward direction; then providinga pad, a terminal and a routing line that include selected portions ofthe conductive layer, including removing selected portions of theconductive layer, wherein the pad, the terminal and the routing lineinclude selected portions of the conductive layer and an electricallyconductive path between the pad and the terminal includes the routingline; mounting a semiconductor device on a heat spreader that includesthe post and the base, wherein the semiconductor device overlaps thepost; electrically connecting the semiconductor device to the pad,thereby electrically connecting the semiconductor device to theterminal; and thermally connecting the semiconductor device to the post,thereby thermally connecting the semiconductor device to the base. 17.The method of claim 16, wherein providing the post and the baseincludes: providing an aluminum plate; forming an etch mask on thealuminum plate that selectively exposes the aluminum plate; etching thealuminum plate in a pattern defined by the etch mask, thereby forming arecess in the aluminum plate that extends into but not through thealuminum plate; then removing the etch mask, wherein the aluminum coreof the post is an unetched portion of the aluminum plate that islaterally surrounded by the recess, and the aluminum core of the base isan unetched portion of the aluminum plate below the recess; thenelectrolessly plating a nickel buffer layer on the aluminum core;electrolessly plating a first copper layer on the nickel buffer layer;and electroplating a second copper layer on the first copper layer,wherein the copper surface layer includes the first and second copperlayers.
 18. The method of claim 16, wherein: providing the adhesiveincludes providing a prepreg with uncured epoxy; flowing the adhesiveincludes melting the uncured epoxy and compressing the uncured epoxybetween the base and the conductive layer; and solidifying the adhesiveincludes curing the uncured epoxy.
 19. The method of claim 16, whereinmounting the semiconductor device includes mounting an LED package thatincludes an LED chip on the pad using a first solder joint and on theheat spreader using a second solder joint, electrically connecting thesemiconductor device includes providing the first solder joint betweenthe LED package and the pad, and thermally connecting the semiconductordevice includes providing the second solder joint between the LEDpackage and the heat spreader.
 20. The method of claim 16, whereinmounting the semiconductor device includes providing a die attachbetween the semiconductor device and the heat spreader, electricallyconnecting the semiconductor device includes providing a wire bondbetween the semiconductor device and the pad, and thermally connectingthe semiconductor device includes providing the die attach between thesemiconductor device and the heat spreader.
 21. A method of making asemiconductor chip assembly, comprising: providing a post, a base, anadhesive and a substrate, wherein the substrate includes a conductivelayer and a dielectric layer, the post is adjacent to the base, extendsabove the base in an upward direction, extends through an opening in theadhesive and extends into an aperture in the substrate, the base extendsbelow the post in a downward direction opposite the upward direction andextends laterally from the post in lateral directions orthogonal to theupward and downward directions, the post and the base include a coppersurface layer and an aluminum core, the copper surface layer conformallycoats and extends above the aluminum core, and the aluminum core of thepost extends above the copper surface layer of the base, the adhesive ismounted on and extends above the base, is sandwiched between the baseand the substrate and is non-solidified, the substrate is mounted on andextends above the adhesive, and the conductive layer extends above thedielectric layer, and a gap is located in the aperture between the postand the substrate; then flowing the adhesive into and upward in the gap;solidifying the adhesive; then providing a heat spreader that includesthe post and the base, wherein providing the heat spreader includesgrinding the post, the adhesive and the conductive layer such that thepost, the adhesive and the conductive layer are laterally aligned withone another at a top lateral surface that includes the copper surfacelayer, excludes the aluminum core and faces in the upward direction;mounting a semiconductor device on the heat spreader, wherein thesemiconductor device overlaps the post, a conductive trace includes apad, a terminal and a selected portion of the conductive layer and thepad is electrically connected to the terminal; electrically connectingthe semiconductor device to the pad, thereby electrically connecting thesemiconductor device to the terminal; and thermally connecting thesemiconductor device to the post, thereby thermally connecting thesemiconductor device to the base.
 22. The method of claim 21, whereinproviding the post and the base includes: providing an aluminum plate;forming an etch mask on the aluminum plate that selectively exposes thealuminum plate; etching the aluminum plate in a pattern defined by theetch mask, thereby forming a recess in the aluminum plate that extendsinto but not through the aluminum plate; then removing the etch mask,wherein the aluminum core of the post is an unetched portion of thealuminum plate that is laterally surrounded by the recess, and thealuminum core of the base is an unetched portion of the aluminum platebelow the recess; and then depositing the copper surface layer over thealuminum core.
 23. The method of claim 21, wherein: providing theadhesive includes providing a prepreg with uncured epoxy; flowing theadhesive includes melting the uncured epoxy and compressing the uncuredepoxy between the base and the substrate; and solidifying the adhesiveincludes curing the uncured epoxy.
 24. The method of claim 21, whereinflowing the adhesive includes filling the gap with the adhesive.
 25. Themethod of claim 21, wherein providing the pad includes removing selectedportions of the conductive layer after solidifying the adhesive.
 26. Themethod of claim 21, wherein providing the pad and the terminal includesremoving selected portions of the conductive layer after solidifying theadhesive.
 27. The method of claim 21, wherein providing the terminalincludes removing selected portions of the base after solidifying theadhesive.
 28. The method of claim 21, wherein providing the heatspreader includes providing a cap that extends above and is adjacent toand covers in the upward direction and extends laterally in the lateraldirections from a top of the post and that overlaps and is adjacent tothe adhesive after grinding the post, the adhesive and the conductivelayer and before mounting the semiconductor device.
 29. The method ofclaim 21, wherein mounting the semiconductor device includes providing afirst solder joint between the semiconductor device and the pad and asecond solder joint between the semiconductor device and the heatspreader, electrically connecting the semiconductor device includesproviding the first solder joint between the semiconductor device andthe pad, and thermally connecting the semiconductor device includesproviding the second solder joint between the semiconductor device andthe heat spreader.
 30. The method of claim 21, wherein mounting thesemiconductor device includes providing a die attach between thesemiconductor device and the heat spreader, electrically connecting thesemiconductor device includes providing a wire bond between thesemiconductor device and the pad, and thermally connecting thesemiconductor device includes providing the die attach between thesemiconductor device and the heat spreader.
 31. A method of making asemiconductor chip assembly, comprising: providing a post and a base,wherein the post is adjacent to and integral with the base and extendsabove the base in an upward direction, the base extends below the postin a downward direction opposite the upward direction and extendslaterally from the post in lateral directions orthogonal to the upwardand downward directions, the post and the base include a copper surfacelayer and an aluminum core, the copper surface layer conformally coatsand extends above the aluminum core, and the aluminum core of the postextends above the copper surface layer of the base, and providing thepost and the base includes: providing an aluminum plate; forming an etchmask on the aluminum plate that selectively exposes the aluminum plate;etching the aluminum plate in a pattern defined by the etch mask,thereby forming a recess in the aluminum plate that extends into but notthrough the aluminum plate; then removing the etch mask, wherein thealuminum core of the post is an unetched portion of the aluminum platethat is laterally surrounded by the recess, and the aluminum core of thebase is an unetched portion of the aluminum plate below the recess; thenelectrolessly plating a nickel buffer layer on the aluminum core;electrolessly plating a first copper layer on the nickel buffer layer;and electroplating a second copper layer on the first copper layer,wherein the copper surface layer includes the first and second copperlayers; providing an adhesive, wherein an opening extends through theadhesive; providing a substrate that includes a conductive layer and adielectric layer, wherein an aperture extends through the substrate;mounting the adhesive on the base, including inserting the post throughthe opening, wherein the adhesive extends above the base and the postextends through the opening; mounting the substrate on the adhesive,including inserting the post into the aperture, wherein the substrateextends above the adhesive, the conductive layer extends above thedielectric layer, the post extends through the opening into theaperture, the adhesive is sandwiched between the base and the substrateand is non-solidified, and a gap is located in the aperture between thepost and the substrate; then applying heat to melt the adhesive; movingthe base and the substrate towards one another, thereby moving the postupward in the aperture and applying pressure to the molten adhesivebetween the base and the substrate, wherein the pressure forces themolten adhesive to flow into and upward in the gap and the post and themolten adhesive extend above the dielectric layer; applying heat tosolidify the molten adhesive, thereby mechanically attaching the postand the base to the substrate; then mounting a semiconductor device on aheat spreader that includes the post and the base, wherein thesemiconductor device overlaps the post, a conductive trace includes apad, a terminal and a selected portion of the conductive layer and thepad is electrically connected to the terminal; electrically connectingthe semiconductor device to the pad, thereby electrically connecting thesemiconductor device to the terminal; and thermally connecting thesemiconductor device to the post, thereby thermally connecting thesemiconductor device to the base.
 32. The method of claim 31, wherein:providing the adhesive includes providing a prepreg with uncured epoxy;flowing the adhesive includes melting the uncured epoxy and compressingthe uncured epoxy between the base and the substrate; and solidifyingthe adhesive includes curing the uncured epoxy.
 33. The method of claim31, wherein providing the pad and the terminal includes removingselected portions of the conductive layer using a second etch mask thatdefines the pad and the terminal after solidifying the adhesive.
 34. Themethod of claim 31, wherein providing the pad includes removing selectedportions of the conductive layer using a second etch mask that definesthe pad after solidifying the adhesive, and providing the terminalincludes removing selected portions of the base using a third etch maskthat defines the terminal after solidifying the adhesive.
 35. The methodof claim 31, wherein providing the heat spreader includes providing acap that extends above and is adjacent to and covers in the upwarddirection and extends laterally in the lateral directions from a top ofthe post and that overlaps and is adjacent to the adhesive using asecond etch mask after solidifying the adhesive and before mounting thesemiconductor device.
 36. A method of making a semiconductor chipassembly, comprising: providing a post and a base, wherein the post isadjacent to and integral with the base and extends above the base in anupward direction, the base extends below the post in a downwarddirection opposite the upward direction and extends laterally from thepost in lateral directions orthogonal to the upward and downwarddirections, the post and the base include a copper surface layer, anickel buffer layer and an aluminum core, the copper surface layerconformally coats and extends above the aluminum core, the aluminum coreof the post extends above the copper surface layer of the base and thenickel buffer layer contacts and is sandwiched between and separates thecopper surface layer and the aluminum core; providing an adhesive,wherein an opening extends through the adhesive; providing a substratethat includes a first conductive layer and a dielectric layer, whereinan aperture extends through the substrate; mounting the adhesive on thebase, including inserting the post through the opening, wherein theadhesive extends above the base and the post extends through theopening; mounting the substrate on the adhesive, including inserting thepost into the aperture, wherein the substrate extends above theadhesive, the first conductive layer extends above the dielectric layer,the post extends through the opening into the aperture, the adhesive issandwiched between the base and the substrate and is non-solidified, anda gap is located in the aperture between the post and the substrate;then applying heat to melt the adhesive; moving the base and thesubstrate towards one another, thereby moving the post upward in theaperture and applying pressure to the molten adhesive between the baseand the substrate, wherein the pressure forces the molten adhesive toflow into and upward in the gap and the post and the molten adhesiveextend above the dielectric layer; applying heat to solidify the moltenadhesive, thereby mechanically attaching the post and the base to thesubstrate; then grinding the post, the adhesive and the conductive layersuch that the post, the adhesive and the conductive layer are laterallyaligned with one another at a top lateral surface that includes thecopper surface layer, excludes the nickel buffer layer and the aluminumcore and faces in the upward direction; then providing a pad and aterminal that include selected portions of the conductive layer,including removing selected portions of the conductive layer; mounting asemiconductor device on a heat spreader that includes the post and thebase, wherein the semiconductor device overlaps the post and the pad iselectrically connected to the terminal; electrically connecting thesemiconductor device to the pad, thereby electrically connecting thesemiconductor device to the terminal; and thermally connecting thesemiconductor device to the post, thereby thermally connecting thesemiconductor device to the base.
 37. The method of claim 36, whereinproviding the post and the base includes: providing an aluminum plate;forming an etch mask on the aluminum plate that selectively exposes thealuminum plate; etching the aluminum plate in a pattern defined by theetch mask, thereby forming a recess in the aluminum plate that extendsinto but not through the aluminum plate; then removing the etch mask,wherein the aluminum core of the post is an unetched portion of thealuminum plate that is laterally surrounded by the recess, and thealuminum core of the base is an unetched portion of the aluminum platebelow the recess; then electrolessly plating a nickel buffer layer onthe aluminum core; electrolessly plating a first copper layer on thenickel buffer layer; and electroplating a second copper layer on thefirst copper layer, wherein the copper surface layer includes the firstand second copper layers.
 38. The method of claim 36, wherein: providingthe adhesive includes providing a prepreg with uncured epoxy; flowingthe adhesive includes melting the uncured epoxy and compressing theuncured epoxy between the base and the substrate; and solidifying theadhesive includes curing the uncured epoxy.
 39. The method of claim 36,wherein mounting the semiconductor device includes mounting an LEDpackage that includes an LED chip on the pad using a first solder jointand on the heat spreader using a second solder joint, electricallyconnecting the semiconductor device includes providing the first solderjoint between the LED package and the pad, and thermally connecting thesemiconductor device includes providing the second solder joint betweenthe LED package and the heat spreader.
 40. The method of claim 36,wherein mounting the semiconductor device includes providing a dieattach between the semiconductor device and the heat spreader,electrically connecting the semiconductor device includes providing awire bond between the semiconductor device and the pad, and thermallyconnecting the semiconductor device includes providing the die attachbetween the semiconductor device and the heat spreader.
 41. A method ofmaking a semiconductor chip assembly, comprising: providing a post and abase, wherein the post is adjacent to and integral with the base andextends above the base in an upward direction, the base extends belowthe post in a downward direction opposite the upward direction andextends laterally from the post in lateral directions orthogonal to theupward and downward directions, the post and the base include a coppersurface layer and an aluminum core, the copper surface layer conformallycoats and extends above the aluminum core, and the aluminum core of thepost extends above the copper surface layer of the base; providing anadhesive, wherein an opening extends through the adhesive; providing aconductive layer, wherein an aperture extends through the conductivelayer; mounting the adhesive on the base, including inserting the postinto the opening, wherein the adhesive extends above the base and thepost extends through the opening; mounting the conductive layer on theadhesive, including aligning the post with the aperture, wherein theconductive layer extends above the adhesive and the adhesive issandwiched between the base and the conductive layer and isnon-solidified; then applying heat to melt the adhesive; moving the baseand the conductive layer towards one another, thereby moving the postupward in the aperture and applying pressure to the molten adhesivebetween the base and the conductive layer, wherein the pressure forcesthe molten adhesive to flow into and upward in a gap located in theaperture between the post and the conductive layer; applying heat tosolidify the molten adhesive, thereby mechanically attaching the postand the base to the conductive layer; then providing a conductive tracethat includes a pad and a terminal, wherein the conductive traceincludes selected portions of the conductive layer and an electricallyconductive path is between the pad and the terminal; providing a heatspreader that includes the post and the base; providing the pad and theheat spreader including: grinding the post, the adhesive and theconductive layer such that the post, the adhesive and the conductivelayer are laterally aligned with one another at a top lateral surfacethat includes the copper surface layer, excludes the aluminum core andfaces in the upward direction; and then removing selected portions ofthe conductive layer using an etch mask that defines the pad; mounting asemiconductor device on the heat spreader, wherein the semiconductordevice overlaps the post; electrically connecting the semiconductordevice to the pad, thereby electrically connecting the semiconductordevice to the terminal; and thermally connecting the semiconductordevice to the post, thereby thermally connecting the semiconductordevice to the base.
 42. The method of claim 41, wherein providing thepost and the base includes: providing an aluminum plate; etching thealuminum plate, thereby forming a recess in the aluminum plate thatextends into but not through the aluminum plate, wherein the aluminumcore of the post is an unetched portion of the aluminum plate that islaterally surrounded by the recess, and the aluminum core of the base isan unetched portion of the aluminum plate below the recess; thenelectrolessly plating a nickel buffer layer on the aluminum core;electrolessly plating a first copper layer on the nickel buffer layer;and electroplating a second copper layer on the first copper layer,wherein the copper surface layer includes the first and second copperlayers.
 43. The method of claim 41, wherein: providing the adhesiveincludes providing a prepreg with uncured epoxy; flowing the adhesiveincludes melting the uncured epoxy and compressing the uncured epoxybetween the base and the conductive layer; and solidifying the adhesiveincludes curing the uncured epoxy.
 44. The method of claim 41, whereinmounting the conductive layer includes mounting the conductive layeralone on the adhesive.
 45. The method of claim 41, including grindingthe adhesive without grinding the post.
 46. A method of making asemiconductor chip assembly, comprising: providing a post and a base,wherein the post is adjacent to and integral with the base and extendsabove the base in an upward direction, the base extends below the postin a downward direction opposite the upward direction and extendslaterally from the post in lateral directions orthogonal to the upwardand downward directions, the post and the base include a copper surfacelayer and an aluminum core, the copper surface layer conformally coatsand extends above the aluminum core, and the aluminum core of the postextends above the copper surface layer of the base; providing anadhesive, wherein an opening extends through the adhesive; providing aconductive layer, wherein an aperture extends through the conductivelayer; mounting the adhesive on the base, including inserting the postinto the opening, wherein the adhesive extends above the base and thepost extends through the opening; mounting the conductive layer on theadhesive, including aligning the post with the aperture, wherein theconductive layer extends above the adhesive and the adhesive issandwiched between the base and the conductive layer and isnon-solidified; then applying heat to melt the adhesive; moving the baseand the conductive layer towards one another, thereby moving the postupward in the aperture and applying pressure to the molten adhesivebetween the base and the conductive layer, wherein the pressure forcesthe molten adhesive to flow into and upward in a gap located in theaperture between the post and the conductive layer; applying heat tosolidify the molten adhesive, thereby mechanically attaching the postand the base to the conductive layer; then providing a conductive tracethat includes a pad and a terminal, wherein the conductive traceincludes selected portions of the conductive layer and an electricallyconductive path is between the pad and the terminal; providing a heatspreader that includes the post and the base; providing the pad and theheat spreader including: grinding the post, the adhesive and theconductive layer such that the post, the adhesive and the conductivelayer are laterally aligned with one another at a top lateral surfacethat includes the copper surface layer, excludes the aluminum core andfaces in the upward direction; then depositing a second conductive layeron the post, the adhesive and the conductive layer; forming an etch maskon the second conductive layer; etching the conductive layers using theetch mask to define the pad; etching the second conductive layer usingthe etch mask to define a cap that extends above and is adjacent to andcovers in the upward direction and extends laterally in the lateraldirections from a top of the post and that overlaps and is adjacent tothe adhesive, wherein the heat spreader includes the cap; and thenremoving the etch mask; mounting a semiconductor device on the cap,wherein the semiconductor device overlaps the post; electricallyconnecting the semiconductor device to the pad, thereby electricallyconnecting the semiconductor device to the terminal; and thermallyconnecting the semiconductor device to the cap, thereby thermallyconnecting the semiconductor device to the base.
 47. The method of claim46, wherein providing the post and the base includes: providing analuminum plate; etching the aluminum plate, thereby forming a recess inthe aluminum plate that extends into but not through the aluminum plate,wherein the aluminum core of the post is an unetched portion of thealuminum plate that is laterally surrounded by the recess, and thealuminum core of the base is an unetched portion of the aluminum platebelow the recess; then electrolessly plating a nickel buffer layer onthe aluminum core; electrolessly plating a first copper layer on thenickel buffer layer; and electroplating a second copper layer on thefirst copper layer, wherein the copper surface layer includes the firstand second copper layers.
 48. The method of claim 46, wherein: providingthe adhesive includes providing a prepreg with uncured epoxy; flowingthe adhesive includes melting the uncured epoxy and compressing theuncured epoxy between the base and the conductive layer; and solidifyingthe adhesive includes curing the uncured epoxy.
 49. The method of claim46, wherein mounting the conductive layer includes mounting theconductive layer alone on the adhesive.
 50. The method of claim 46,including grinding the adhesive without grinding the post.
 51. A methodof making a semiconductor chip assembly, comprising: providing a postand a base, wherein the post is adjacent to and integral with the baseand extends above the base in an upward direction, the base extendsbelow the post in a downward direction opposite the upward direction andextends laterally from the post in lateral directions orthogonal to theupward and downward directions, the post and the base include a coppersurface layer and an aluminum core, the copper surface layer conformallycoats and extends above the aluminum core, and the aluminum core of thepost extends above the copper surface layer of the base; providing anadhesive, wherein an opening extends through the adhesive; providing asubstrate that includes a conductive layer and a dielectric layer,wherein an aperture extends through the substrate; mounting the adhesiveon the base, including inserting the post through the opening, whereinthe adhesive extends above the base and the post extends through theopening; mounting the substrate on the adhesive, including inserting thepost into the aperture, wherein the substrate extends above theadhesive, the conductive layer extends above the dielectric layer, thepost extends through the opening into the aperture, the adhesive issandwiched between the base and the substrate and is non-solidified, anda gap is located in the aperture between the post and the substrate;then applying heat to melt the adhesive; moving the base and thesubstrate towards one another, thereby moving the post upward in theaperture and applying pressure to the molten adhesive between the baseand the substrate, wherein the pressure forces the molten adhesive toflow into and upward in the gap and the post and the molten adhesiveextend above the dielectric layer; applying heat to solidify the moltenadhesive, thereby mechanically attaching the post and the base to thesubstrate; then providing a conductive trace that includes a pad, aterminal and a selected portion of the conductive layer, wherein the padis electrically connected to the terminal; providing a heat spreaderthat includes the post and the base; providing the pad and the heatspreader including: grinding the post, the adhesive and the conductivelayer such that the post, the adhesive and the conductive layer arelaterally aligned with one another at a top lateral surface thatincludes the copper surface layer, excludes the aluminum core and facesin the upward direction; and then removing selected portions of theconductive layer using an etch mask that defines the pad; mounting asemiconductor device on the heat spreader, wherein the semiconductordevice overlaps the post; electrically connecting the semiconductordevice to the pad, thereby electrically connecting the semiconductordevice to the terminal; and thermally connecting the semiconductordevice to the post, thereby thermally connecting the semiconductordevice to the base.
 52. The method of claim 51, wherein providing thepost and the base includes: providing an aluminum plate; etching thealuminum plate, thereby forming a recess in the aluminum plate thatextends into but not through the aluminum plate, wherein the aluminumcore of the post is an unetched portion of the aluminum plate that islaterally surrounded by the recess, and the aluminum core of the base isan unetched portion of the aluminum plate below the recess; thenelectrolessly plating a nickel buffer layer on the aluminum core;electrolessly plating a first copper layer on the nickel buffer layer;and electroplating a second copper layer on the first copper layer,wherein the copper surface layer includes the first and second copperlayers.
 53. The method of claim 51, wherein: providing the adhesiveincludes providing a prepreg with uncured epoxy; flowing the adhesiveincludes melting the uncured epoxy and compressing the uncured epoxybetween the base and the conductive layer; and solidifying the adhesiveincludes curing the uncured epoxy.
 54. The method of claim 51, includinggrinding the adhesive without grinding the post.
 55. The method of claim51, including using the etch mask to define the terminal.
 56. A methodof making a semiconductor chip assembly, comprising: providing a postand a base, wherein the post is adjacent to and integral with the baseand extends above the base in an upward direction, the base extendsbelow the post in a downward direction opposite the upward direction andextends laterally from the post in lateral directions orthogonal to theupward and downward directions, the post and the base include a coppersurface layer and an aluminum core, the copper surface layer conformallycoats and extends above the aluminum core, and the aluminum core of thepost extends above the copper surface layer of the base; providing anadhesive, wherein an opening extends through the adhesive; providing asubstrate that includes a conductive layer and a dielectric layer,wherein an aperture extends through the substrate; mounting the adhesiveon the base, including inserting the post through the opening, whereinthe adhesive extends above the base and the post extends through theopening; mounting the substrate on the adhesive, including inserting thepost into the aperture, wherein the substrate extends above theadhesive, the conductive layer extends above the dielectric layer, thepost extends through the opening into the aperture, the adhesive issandwiched between the base and the substrate and is non-solidified, anda gap is located in the aperture between the post and the substrate;then applying heat to melt the adhesive; moving the base and thesubstrate towards one another, thereby moving the post upward in theaperture and applying pressure to the molten adhesive between the baseand the substrate, wherein the pressure forces the molten adhesive toflow into and upward in the gap and the post and the molten adhesiveextend above the dielectric layer; applying heat to solidify the moltenadhesive, thereby mechanically attaching the post and the base to thesubstrate; then providing a conductive trace that includes a pad, aterminal and a selected portion of the conductive layer, wherein the padis electrically connected to the terminal; providing a heat spreaderthat includes the post and the base; providing the pad and the heatspreader including: grinding the post, the adhesive and the conductivelayer such that the post, the adhesive and the conductive layer arelaterally aligned with one another at a top lateral surface thatincludes the copper surface layer, excludes the aluminum core and facesin the upward direction; then depositing a second conductive layer onthe post, the adhesive and the conductive layer; forming an etch mask onthe second conductive layer; etching the conductive layers using theetch mask to define the pad; etching the second conductive layer usingthe etch mask to define a cap that extends above and is adjacent to andcovers in the upward direction and extends laterally in the lateraldirections from a top of the post and that overlaps and is adjacent tothe adhesive, wherein the heat spreader includes the cap; and thenremoving the etch mask; mounting a semiconductor device on the cap,wherein the semiconductor device overlaps the post; electricallyconnecting the semiconductor device to the pad, thereby electricallyconnecting the semiconductor device to the terminal; and thermallyconnecting the semiconductor device to the cap, thereby thermallyconnecting the semiconductor device to the base.
 57. The method of claim56, wherein providing the post and the base includes: providing analuminum plate; etching the aluminum plate, thereby forming a recess inthe aluminum plate that extends into but not through the aluminum plate,wherein the aluminum core of the post is an unetched portion of thealuminum plate that is laterally surrounded by the recess, and thealuminum core of the base is an unetched portion of the aluminum platebelow the recess; then electrolessly plating a nickel buffer layer onthe aluminum core; electrolessly plating a first copper layer on thenickel buffer layer; and electroplating a second copper layer on thefirst copper layer, wherein the copper surface layer includes the firstand second copper layers.
 58. The method of claim 56, wherein: providingthe adhesive includes providing a prepreg with uncured epoxy; flowingthe adhesive includes melting the uncured epoxy and compressing theuncured epoxy between the base and the conductive layer; and solidifyingthe adhesive includes curing the uncured epoxy.
 59. The method of claim56, including grinding the adhesive without grinding the post.
 60. Themethod of claim 56, including etching the conductive layers using theetch mask to define the terminal.